The three forces acting on the water tank represent the effect of the wind. Replace this system by a single resultant force and specify its vertical location from point O.

R = 600 lb, d = 65.0 ft below O

R = 600 lb, d = 130.4 ft below O

R = 600 lb, d = 65.0 ft above O

R = 600 lb, d = 130.4 ft above O

The cable AO exerts a force on the top of the pole of F = { 120i 90j 80k} lb. If the cable has a length of 34 ft, determine the height z of the pole and the location (x,y) of its base.

x = 16 ft, y = 16 ft, z = 25 ft

x = 20 ft, y = 10 ft, z = 14 ft

x = 24 ft, y = 18 ft, z = 16 ft

The main beam along the wing of an airplane is swept back at an angle of 25 . From load calculations it is determined that the beam is subjected to couple moments aMx = 25,000 lb ft and My = 17,000 lb ft. Determine the equivalent couple moments created about the x' and y' axis.

Mx' = 29.8 kip-ft, My' = 4.84 kip-ft

Mx' = 26.0 kip-ft, My' = 29.8 kip-ft

Mx' = 29.8 kip-ft, My' = -4.84 kip-ft

Mx' = 26.0 kip-ft, My' = 15.47 kip-ft

Mx' = 29.8 kip-ft, My' = 4.84 kip-ft

Compute the force in each member of the Warren truss and indicate whether the members are in tension or compression. All the members are 3 m long.

AB = CD = 8.00 kN T, AE = DE = 6.92 kN C, BE = CE = 8.00 kN C, BC = 6.92 kN T

AB = CD = 8.00 kN C, AE = DE = 6.92 kN T, BE = CE = 8.00 kN T, BC = 6.92 kN C

AB = CD = 4.62 kN C, AE = DE = 2.31 kN T, BE = CE = 4.62 kN T, BC = 2.31 kN C

AB = CD = 8.00 kN T, AE = DE = 6.92 kN C, BE = CE = 8.00 kN C, BC = 6.92 kN T

AB = CD = 4.62 kN T, AE = DE = 2.31 kN C, BE = CE = 4.62 kN C, BC = 2.31 kN T

A sign is subjected to a wind loading that exerts horizontal forces of 300 lb on joints B and C of one of the side supporting trusses. Determine the force in members BC, CD, DB, and DE of the truss and state whether the members are in tension or compression.

CB = 125 lb T, CD = 325 lb C, DB = 0, DE = 325 lb C

CB = 720 lb C, CD = 780 lb T, DB = 0, DE = 780 lb T

CB = 720 lb T, CD = 780 lb C, DB = 0, DE = 780 lb C

CB = 125 lb T, CD = 325 lb C, DB = 0, DE = 325 lb C

CB = 125 lb C, CD = 325 lb T, DB = 0, DE = 325 lb T

A tower used in an electrical substation supports a power line which exerts a horizontal tension of T = 500 lb on each side truss of the tower as shown. Determine the force in members BC, CM, and LM of a side truss and indicate whether the members are in tension or compression.

CM = 581 lb T, CB = 2050 lb C, LM = 2000 lb T

CM = 833 lb T, CB = 3330 lb C, LM = 2670 lb T

CM = 581 lb T, CB = 2050 lb C, LM = 2000 lb T

CM = 325 lb T, CB = 3040 lb C, LM = 2670 lb T

CM = 58 lb T, CB = 1646 lb C, LM = 1600 lb T

Determine the force in members FF, FB, and BC of the Fink truss and indicate whether the members are in tension or compression.

BF = 8660 lb C, FG = 3600 lb C, BC = 1212 lb T

BF = 693 lb T, FG = 1800 lb C, BC = 1212 lb T

BF = 8660 lb C, FG = 3600 lb C, BC = 1212 lb T

BF = 3810 lb T, FG = 3600 lb C, BC = 1212 lb T

BF = 1732 lb T, FG = 2400 lb C, BC = 1212 lb T

The Warren truss is used to support a staircase. Determine the force in members CE, ED, and DF, and state whether the members are in tension or compression. Assume all joints are pinned.

ED = 3.60 kN T, DF = 1.70 kN C, CE = 6.22 kN C

ED = 2.00 kN C, DF = 2.26 kN C, CE = 2.26 kN T

ED = 0.800 kN C, DF = 1.131 kN T, CE = 2.83 kN C

ED = 0.400 kN C, DF = 2.26 kN T, CE = 4.53 kN C

The Pratt bridge truss is subjected to the loading shown. Determine the force in members CD, CL and ML, and indicate whether these members are in tension or compression.

CL = 100 kN C, ML = 150 kN C, CD = 150 kN T

CL = 100 kN T, ML = 150 kN T, CD = 150 kN C

CL = 50 kN C, ML = 112.5 kN C, CD = 112.5 kN T

CL = 100 kN C, ML = 150 kN C, CD = 150 kN T

CL = 50 kN T, ML = 112.5 kN T, CD = 112.5 kN C

The hoist supports the 125-kg engine. Determine the force the load creates in member DB and in member FB, which contains the hydraulic cylinder H.

FB = 1.839 kN C, BD = 2.47 kN T

FB = 1.939 kN C, BD = 2.60 kN T

FB = 1.839 kN C, BD = 2.47 kN T

FB = 1.839 kN C, BD = 2.60 kN T

A Russell's traction is used for immobilizing femoral fractures C. If the lower leg has a weight of 8 lb, determine the weight W that must be suspended at D in order for the leg to be held in the position shown. Also, what is the tension force F in the femur and the distance which locates the center of gravity G of the lower leg? Neglect the size of the pulley at B.

x = 1.33 ft, w = 15.76 lb, F = 20.0 lb

x = 1.44 ft, w = 10.8 lb, F = 12.61 lb

x = 1.33 ft, w = 15.76 lb, F = 20.0 lb

x = 1.56 ft, w = 9.75 lb, F = 12.69 lb

x = 0.869 ft, w = 6.44 lb, F = 5.03 lb

78 + Mcqs in Engineering Mechanics in Engineering Page 1 McqOptions

1.	The three forces acting on the water tank represent the effect of the wind. Replace this system by a single resultant force and specify its vertical location from point O.
A.	R = 600 lb, d = 65.0 ft below O
B.	R = 600 lb, d = 130.4 ft below O
C.	R = 600 lb, d = 65.0 ft above O
D.	R = 600 lb, d = 130.4 ft above O
Answer» E.

Discussion

2.	Determine the magnitude and direction of the couple moment.
A.	M = 3900 lb-ft CW
B.	M = 3900 lb-ft CCW
C.	M = 3120 lb-ft CW
D.	M = 3120 lb-ft CCW
Answer» E.

Discussion

3.	Replace the loading by an equivalent force and couple moment acting at point O.
A.	R = 90 kN, M = 473 kN-m CW
B.	R = 90 kN, M = 338 kN-m CW
C.	R = 45 kN, M = 203 kN-m CW
D.	R = 135 kN, M = 270 kN-m CW
Answer» C. R = 45 kN, M = 203 kN-m CW

Discussion

4.	The bricks on top of the beam and the supports at the bottom create the distributed loading shown in the second figure. Determine the required intensity w and dimension d of the right support so that the resultant force and couple moment about point A of the system are both zero.
A.	w = 175.0 N/m, d = 1.5 m
B.	w = 138.2 N/m, d = 1.9 m
C.	w = 125.0 N/m, d = 2.1 m
D.	w = 154.4 N/m, d = 1.7 m
Answer» B. w = 138.2 N/m, d = 1.9 m

Discussion

5.	Determine the magnitude of the x and y components of the 700-lb force.
A.	Fx = -350 lb, Fy = 606 lb
B.	Fx = -404 lb, Fy = 571 lb
C.	Fx = -606 lb, Fy = 350 lb
D.	Fx = -571 lb, Fy = 404 lb
Answer» D. Fx = -571 lb, Fy = 404 lb

Discussion

6.	The cable AO exerts a force on the top of the pole of F = { 120i 90j 80k} lb. If the cable has a length of 34 ft, determine the height z of the pole and the location (x,y) of its base.
A.	x = 16 ft, y = 16 ft, z = 25 ft
B.	x = 12 ft, y = 9 ft, z = 8 ft
C.	x = 20 ft, y = 10 ft, z = 14 ft
D.	x = 24 ft, y = 18 ft, z = 16 ft
Answer» E.

Discussion

7.	The cord is attached between two walls. If it is 8 m long, determine the distance x to the point of attachment at B.
A.	x = 7.75 m
B.	x = 7.68 m
C.	x = 6.93 m
D.	x = 7.94 m
Answer» C. x = 6.93 m

Discussion

8.	The main beam along the wing of an airplane is swept back at an angle of 25 . From load calculations it is determined that the beam is subjected to couple moments aM_x = 25,000 lb ft and M_y = 17,000 lb ft. Determine the equivalent couple moments created about the x' and y' axis.
A.	Mx' = 26.0 kip-ft, My' = 29.8 kip-ft
B.	Mx' = 29.8 kip-ft, My' = -4.84 kip-ft
C.	Mx' = 26.0 kip-ft, My' = 15.47 kip-ft
D.	Mx' = 29.8 kip-ft, My' = 4.84 kip-ft
Answer» D. Mx' = 29.8 kip-ft, My' = 4.84 kip-ft

Discussion

9.	The principles of a differential chain block are indicated schematically in the figure. Determine the magnitude of force P needed to support the 800-N force. Also compute the distance x where the cable must be attached to bar AB so the bar remains horizontal. All pulleys have a radius of 60 mm.
A.	P = 80 N, x = 240 mm
B.	P = 80 N, x = 180 mm
C.	P = 40 N, x = 180 mm
D.	P = 40 N, x = 240 mm
Answer» E.

Discussion

10.	Compute the force in each member of the Warren truss and indicate whether the members are in tension or compression. All the members are 3 m long.
A.	AB = CD = 8.00 kN C, AE = DE = 6.92 kN T, BE = CE = 8.00 kN T, BC = 6.92 kN C
B.	AB = CD = 4.62 kN C, AE = DE = 2.31 kN T, BE = CE = 4.62 kN T, BC = 2.31 kN C
C.	AB = CD = 8.00 kN T, AE = DE = 6.92 kN C, BE = CE = 8.00 kN C, BC = 6.92 kN T
D.	AB = CD = 4.62 kN T, AE = DE = 2.31 kN C, BE = CE = 4.62 kN C, BC = 2.31 kN T
Answer» C. AB = CD = 8.00 kN T, AE = DE = 6.92 kN C, BE = CE = 8.00 kN C, BC = 6.92 kN T

Discussion

11.	A sign is subjected to a wind loading that exerts horizontal forces of 300 lb on joints B and C of one of the side supporting trusses. Determine the force in members BC, CD, DB, and DE of the truss and state whether the members are in tension or compression.
A.	CB = 720 lb C, CD = 780 lb T, DB = 0, DE = 780 lb T
B.	CB = 720 lb T, CD = 780 lb C, DB = 0, DE = 780 lb C
C.	CB = 125 lb T, CD = 325 lb C, DB = 0, DE = 325 lb C
D.	CB = 125 lb C, CD = 325 lb T, DB = 0, DE = 325 lb T
Answer» C. CB = 125 lb T, CD = 325 lb C, DB = 0, DE = 325 lb C

Discussion

12.	A tower used in an electrical substation supports a power line which exerts a horizontal tension of T = 500 lb on each side truss of the tower as shown. Determine the force in members BC, CM, and LM of a side truss and indicate whether the members are in tension or compression.
A.	CM = 833 lb T, CB = 3330 lb C, LM = 2670 lb T
B.	CM = 581 lb T, CB = 2050 lb C, LM = 2000 lb T
C.	CM = 325 lb T, CB = 3040 lb C, LM = 2670 lb T
D.	CM = 58 lb T, CB = 1646 lb C, LM = 1600 lb T
Answer» B. CM = 581 lb T, CB = 2050 lb C, LM = 2000 lb T

Discussion

13.	Determine the force in members FF, FB, and BC of the Fink truss and indicate whether the members are in tension or compression.
A.	BF = 693 lb T, FG = 1800 lb C, BC = 1212 lb T
B.	BF = 8660 lb C, FG = 3600 lb C, BC = 1212 lb T
C.	BF = 3810 lb T, FG = 3600 lb C, BC = 1212 lb T
D.	BF = 1732 lb T, FG = 2400 lb C, BC = 1212 lb T
Answer» B. BF = 8660 lb C, FG = 3600 lb C, BC = 1212 lb T

Discussion

14.	The flying boom B is used with a crane to position construction materials in coves and underhangs. The horizontal "balance" of the boom is controlled by a 250-kg block D, which has a center of gravity at G and moves by internal sensing devices along the bottom flange F of the beam. Determine the position x of the block when the boom is used to lift the stone S, which has a mass of 60 kg. The boom is uniform and has a mass of 80 kg.
A.	x = 2.500 m
B.	x = 0.340 m
C.	x = 1.180 m
D.	x = 0.600 m
Answer» C. x = 1.180 m

Discussion

15.	A smooth can C, having a mass of 2 kg, is lifted from a feed at A to a ramp at B by a forked rotating rod. If the rod maintains a constant angular motion of = 0.5 rad/s, determine the force which the rod exerts on the can at the instant = 30 . Neglect the effects of friction in the calculation. The ramp from A to B is circular, having a radius of 700 min.
A.	F = 19.62 N
B.	F = 11.33 N
C.	F = 10.63 N
D.	F = 12.03 N
Answer» C. F = 10.63 N

Discussion

16.	A car is traveling along the circular curve of radius r = 300 ft. At the instant shown, its angular rate of rotation is = 0.4 rad / s, which is increasing at the rate of = 0.2 rad / s². Determine the magnitude of the velocity of the car at this instant.
A.	v = 120.0 ft/s
B.	v = 0
C.	v = 60.0 ft/s
D.	v = 169.7 ft/s
Answer» B. v = 0

Discussion

17.	A ball is thrown downward on the 30 inclined plane so that when it rebounds perpendicular to the incline it has a velocity of v_A = 40 ft/s. Determine the distance R where it strikes the plane at B.
A.	R = 66.3 ft
B.	R = 99.4 ft
C.	R = 172.1 ft
D.	R = 344 ft
Answer» B. R = 99.4 ft

Discussion

18.	The spool, which has a weight of 2lb, slides along the smooth horizontal spiral rod, r = (2) ft, where is in radians. If its angular rate of rotation is constant and equals = 4 rad/s, determine the tangential force P needed to cause the motion and the normal force that the spool exerts on the rod at the instant = 90 .
A.	P = 0.499 lb, N = 5.03 lb
B.	P = 5.50 lb, N = 15.65 lb
C.	P = 3.35 lb, N = 2.43 lb
D.	P = 1.677 lb, N = 4.77 lb
Answer» E.

Discussion

19.	The floor beams AB and BC are stiffened using the two tie rods CD and AD. Determine the force along each rod. Assume the three contacting members at B are smooth and the joints at A, C, and D are pins.
A.	T = 480 lb
B.	T = 520 lb
C.	T = 1248 lb
D.	T = 1152 lb
Answer» D. T = 1152 lb

Discussion

20.	The Warren truss is used to support a staircase. Determine the force in members CE, ED, and DF, and state whether the members are in tension or compression. Assume all joints are pinned.
A.	ED = 3.60 kN T, DF = 1.70 kN C, CE = 6.22 kN C
B.	ED = 2.00 kN C, DF = 2.26 kN C, CE = 2.26 kN T
C.	ED = 0.800 kN C, DF = 1.131 kN T, CE = 2.83 kN C
D.	ED = 0.400 kN C, DF = 2.26 kN T, CE = 4.53 kN C
Answer» E.

Discussion

21.	A race car starting from rest moves along a straight track with an acceleration as shown in the graph (where for t 10 s, a = 8 m/s²). Determine the time t for the car to reach a speed of 50 m/s.
A.	t = 11.25 s
B.	t = 6.25 s
C.	t = 12.5 s
D.	t = 3.53 s
Answer» B. t = 6.25 s

Discussion

22.	A two-stage missile is fired vertically from rest with an acceleration as shown in the graph. In 15 s the first stage A burns out and the second stage B ignites. How fast is the rocket moving and how far has it gone at t = 20 s? How fast is the missile moving and how far has it gone at t = 20 s?
A.	v = 430 m/s, s = 4.30 km
B.	v = 395 m/s, s = 3.69 km
C.	v = 360 m/s, s = 3.60 km
D.	v = 500 m/s, s = 5.00 km
Answer» C. v = 360 m/s, s = 3.60 km

Discussion

23.	A 1.5-lb brick is released from rest A and slides down the inclined roof. If the coefficient of friction between the roof and the brick is = 0.3, determine the speed at which the brick strikes the gutter G.
A.	v = 3.00 ft/s
B.	v = 2.68 ft/s
C.	v = 5.61 ft/s
D.	v = 15.23 ft/s
Answer» E.

Discussion

24.	Gear A is in mesh with gear B as shown. If A starts from rest and has a constant angular acceleration of _A = 2 rad/s², determine the tome needed for B to attain an angular velocity of _B = 50 rad/s.
A.	t = 62.5 s
B.	t = 250.0 s
C.	t = 10.00 s
D.	t = 40.0 s
Answer» B. t = 250.0 s

Discussion

25.	A hockey puck is traveling to the left with a velocity of v₁ = 10 m/s when it is struck by a hockey stick and given a velocity of v₂ = 20 m/s as shown. Determine the magnitude of the net impulse exerted by the hockey stick on the puck. The puck has a mass of 0.2 kg.
A.	Imp = 6.00 N-s
B.	Imp = 2.00 N-s
C.	Imp = 2.78 N-s
D.	Imp = 5.68 N-s
Answer» E.

Discussion

26.	A car is traveling at a speed of 80 ft/s when the brakes are suddenly applied, causing a constant deceleration of 10 ft/s². Determine the time required to stop the car and the distance traveled before stopping.
A.	t = 8 s, s = 800 ft
B.	t = 8 s, s = 320 ft
C.	t = 4 s, s = 240 ft
D.	t = 4 s, s = 40 ft
Answer» C. t = 4 s, s = 240 ft

Discussion

27.	An electric train car, having a mass of 25 Mg, travels up a 10 incline with a constant speed of 80 km/h. Determine the power required to overcome the force of gravity.
A.	P = 961 kW
B.	P = 346 kW
C.	P = 341 kW
D.	P = 946 kW
Answer» E.

Discussion

28.	A car is equipped with a bumper B designed to absorb collisions. The bumper is mounted to the car using pieces of flexible tubing T. Upon collision with a rigid barrier A, a constant horizontal force F is developed which causes a car deceleration of 3g = 29.43 m/s² (the highest safe deceleration for a passenger without a seatbelt). If the car and passenger have a total mass of 1.5 Mg and the car is initially coasting with a speed of 1.5 m/s, compute the magnitude of F needed to stop the car and the deformation x of the bumper tubing.
A.	F = 44.1 kN, x = 38.2 mm
B.	F = 22.1 kN, x = 76.4 mm
C.	F = 22.1 kN, x = 38.2 mm
D.	F = 44.1 kN, x = 76.4 mm
Answer» B. F = 22.1 kN, x = 76.4 mm

Discussion

29.	A motor hoists a 50-kg crate at constant speed to a height of h = 6 m in 3 s. If the indicated power of the motor is 4 kw, determine the motor's efficiency.
A.	e = 0.025 (2.5%)
B.	e = 0.245 (24.5%)
C.	e = 0.736 (73.6%)
D.	e = 0.05 (5.0%)
Answer» C. e = 0.736 (73.6%)

Discussion

30.	A truck has a weight of 25,000 lb and an engine which transmits a power of 350hp. Assuming that the wheels do not slip on the ground, determine the angle of the largest incline the truck can climb at a constant speed of v = 50 ft/s.
A.	2 = 8.86E
B.	2 = 24.3E
C.	2 = 8.75E
D.	2 = 26.8E
Answer» B. 2 = 24.3E

Discussion

31.	A boy twirls a 15-lb bucket of water in a vertical circle. If the radius of curvature of the path is 4 ft, determine the minimum speed the bucket must have when it is overhead at A so no water spills out.
A.	v = 11.35 ft/s
B.	v = 0
C.	v = 6.26 ft/s
D.	v = 2.83 ft/s
Answer» B. v = 0

Discussion

32.	In cases of emergency, the gas actuator can be used to move a 75-kg block B by exploding a charge C near a pressurized cylinder of negligible mass. As a result of the explosion, the cylinder fractures and the released gas forces the front part ofthe cylinder, A, to move B and the floor is = 0.5, determine the impulse that the actuator must impart to B.
A.	Imp = 147.2 N-s
B.	Imp = 132.2 N-s
C.	Imp = 15.00 N-s
D.	Imp = 162.2 N-s
Answer» E.

Discussion

33.	Determine the magnitude of the forces in pins B and D of the four-member frame.
A.	B = 503 lb, D = 225 lb
B.	B = 225 lb, D = 503 lb
C.	B = 56.3 lb, D = 125.8 lb
D.	B = 125.8 lb, D = 112.5 lb
Answer» D. B = 125.8 lb, D = 112.5 lb

Discussion

34.	The Pratt bridge truss is subjected to the loading shown. Determine the force in members CD, CL and ML, and indicate whether these members are in tension or compression.
A.	CL = 100 kN T, ML = 150 kN T, CD = 150 kN C
B.	CL = 50 kN C, ML = 112.5 kN C, CD = 112.5 kN T
C.	CL = 100 kN C, ML = 150 kN C, CD = 150 kN T
D.	CL = 50 kN T, ML = 112.5 kN T, CD = 112.5 kN C
Answer» C. CL = 100 kN C, ML = 150 kN C, CD = 150 kN T

Discussion

35.	The uniform slender rod has a mass of 5 kg. Determine the magnitude of the reaction at the pin O when the cord at A is cut and = 90
A.	O = 42.0 N
B.	O = 91.1 N
C.	O = 122.6 N
D.	O = 67.4 N
Answer» C. O = 122.6 N

Discussion

36.	The elevator E and its freight have a total mass of 400 kg. Hoisting is provided by the motor M and the 60-kg block C. If the motor has an efficiency of e = 0.6, determine the power that must be supplied to the motor when the elevator is hoisted upward at a constant speed of v_E = m/s.
A.	P = 22.2 kW
B.	P = 13.34 kW
C.	P = 26.2 kW
D.	P = 30.1 kW
Answer» B. P = 13.34 kW

Discussion

37.	The firing mechanism of a pinball machine consists of a plunger P having a mass of 0.25 kg and a spring of stiffness k = 300 N/m. When s = 0, the spring is compressed 50 mm. If the arm is pulled back such that s = 100 mm and released, determine the speed of the 0.3 kg pinball B just before the plunger strikes the stop, i.e., s = 0. Assume all sufaces of contact to be smooth. The ball moves in the horizontal plane. Note that the ball slides without rolling.
A.	v = 4.47 m/s
B.	v = 3.30 m/s
C.	v = 2.34 m/s
D.	v = 3.16 m/s
Answer» C. v = 2.34 m/s

Discussion

38.	The boy at D has a mass of 50 kg, a center of mass at G, and stands on a plank at the position shown. The plank is pin-supported at A and rests on a post at B. Neglecting the weight of the plank and post, determine the magnitude of force P his friend (?) at E must exert in order to pull out the post. Take _B = 0.3 and _C = 0.8.
A.	P = 360 N
B.	P = 264 N
C.	P = 229 N
D.	P = 293 N
Answer» C. P = 229 N

Discussion

39.	The refrigerator has a weight of 200 lb and a center of gravity at G. Determine the force P required to move it. Will the refrigerator tip or slip? Take = 0.4.
A.	P = 75 lb Slips
B.	P = 80 lb Tips
C.	P = 80 lb Slips
D.	P = 75 lb Tips
Answer» E.

Discussion

40.	A 17-kg ladder has a center of mass at G. If the coefficients of friction at A and B are _A = 0.3 and _B = 0.2, respectively, determine the smallest horizontal force that the man must exert of the ladder at point C in order to push the ladder forward.
A.	F = 120.2 N
B.	F = 288 N
C.	F = 166.8 N
D.	F = 204 N
Answer» E.

Discussion

41.	The wind has blown sand over a platform such that the intensity of load can be approximated by the function . Simplify this distributed loading to a single concentrated force and specify the magnitude and location of the force measured from A.
A.	R = 1250 N, x = 6.67 m
B.	R = 2500 N, x = 6.67 m
C.	R = 1250 N, x = 8 m
D.	R = 2500 N, x = 8 m
Answer» D. R = 2500 N, x = 8 m

Discussion

42.	The scissors lift consists of two sets of symmetrically placed cross members (one in front that is shown and one behind that is not shown) and two hydraulic cylinders (front [labeled DE] and back [not shown]). The uniform platform has a mass of 60 kg with a center of gravity at G1. The 85 kg load (center of gravity at G2) is centered front to back. Determine the force in each of the hydraulic cylinders necessary to maintain equilibrium. These are rollers at B and D.
A.	DE = 1.067 kN C
B.	DE = 1.139 kN C
C.	DE = 0.606 kN C
D.	DE = 1.207 kN C
Answer» B. DE = 1.139 kN C

Discussion

43.	The hoist supports the 125-kg engine. Determine the force the load creates in member DB and in member FB, which contains the hydraulic cylinder H.
A.	FB = 5.82 kN C, BD = 7.80 kN T
B.	FB = 1.939 kN C, BD = 2.60 kN T
C.	FB = 1.839 kN C, BD = 2.47 kN T
D.	FB = 1.839 kN C, BD = 2.60 kN T
Answer» C. FB = 1.839 kN C, BD = 2.47 kN T

Discussion

44.	The 2-kg shaft CA passes through a smooth journal bearing at B. Initially, the springs, which are coiled loosely around the shaft, are unstretched when no force is applied to the shaft. In this position s = s = 250 and the shaft is originally at rest. If a horizontal force of F = 5 kN is applied, determine the speed of the shaft at the instant s = 50 mm, s = 450 mm. The ends of the springs are attached to the bearing at B and the caps at C and A.
A.	v = 31.6 m/s
B.	v = 14.14 m/s
C.	v = 44.7 m/s
D.	v = 30.0 m/s
Answer» E.

Discussion

45.	A car, assumed to be rigid and having a mass of 800 kg, strikes a barrel-barrier installation without the driver applying the brakes. From experiments, the magnitude of the force of resistance F_r, created by deforming the barrels successively, is shown as a function of vehicle penetration. If the car strikes the barrier traveling at V_c = 70 km/h, determine approximately the distance s to which the car penetrates the barrier.
A.	s = 1.890 m
B.	s = 4.72 m
C.	s = 2.77 m
D.	s = 2.52 m
Answer» D. s = 2.52 m

Discussion

46.	A motor supplies a constant torque or twist of M = 120 lb ft to the drum. If the drum has a weight of 30 lb and a radius of gyration of k₀ = 0.8ft, determine the speed of the 15-lb carte A after it rises s = 4 ft starting from rest. Neglect the weight of the cord.
A.	v = 49.1 ft/s
B.	v = 29.6 ft/s
C.	v = 26.7 ft/s
D.	v = 44.3 ft/s
Answer» D. v = 44.3 ft/s

Discussion

47.	The boys A, B and C stand near the edges of a raft as shown. Determine the location (x, y) of boy D so that all four boys create a single resultant force acting through the raft's center O. Provided the raft itself is symmetric, this would keep the raft afloat in a horizontal plane. the mass of each boy is indicated in the diagram.
A.	x = 4.5 m, y = 1.5 m
B.	x = 3.0 m, y = 3.0 m
C.	x = 1.5 m, y = 4.5 m
D.	x = 3.0 m, y = 4.0 m
Answer» D. x = 3.0 m, y = 4.0 m

Discussion

48.	A Russell's traction is used for immobilizing femoral fractures C. If the lower leg has a weight of 8 lb, determine the weight W that must be suspended at D in order for the leg to be held in the position shown. Also, what is the tension force F in the femur and the distance which locates the center of gravity G of the lower leg? Neglect the size of the pulley at B.
A.	x = 1.44 ft, w = 10.8 lb, F = 12.61 lb
B.	x = 1.33 ft, w = 15.76 lb, F = 20.0 lb
C.	x = 1.56 ft, w = 9.75 lb, F = 12.69 lb
D.	x = 0.869 ft, w = 6.44 lb, F = 5.03 lb
Answer» B. x = 1.33 ft, w = 15.76 lb, F = 20.0 lb

Discussion

49.	Gear A has a weight of 1.5 lb, a radius of 0.2 ft, and a radius of gyration of k_o = 0.13ft. The coefficient of friction between the gear rack B and the horizontal surface is = 0.3. If the rack has a weight of 0.8 lb and is initially sliding to the left with a velocity of (v_B)₂ = 8 ft/s to the left. Neglect friction between the rack and the gear and assume that the gear exerts only a horizontal force on the rack.
A.	M = 0.01425 lb-ft
B.	M = 0.00630 lb-ft
C.	M = 0.0622 lb-ft
D.	M = 0.0560 lb-ft
Answer» D. M = 0.0560 lb-ft

Discussion

50.	The 50-kg cylinder has an angular velocity of 30 rad/s when it is brought into contact with the horizontal surface at C. If the coefficient of friction is _c = 0.2, determine how long it takes for the cylinder to stop spinning. What force is developed at the pin A during this time? The axis of the cylinder is connected to two symmetrical links. (Only AB is shown.) For the computation, neglect the weight of the links.
A.	t = 1.529 s, A = 0
B.	t = 3.06 s, A = 0
C.	t = 1.529 s, A = 49.1 N
D.	t = 3.06 s, A = 49.1 N
Answer» D. t = 3.06 s, A = 49.1 N

Discussion

Explore topic-wise MCQs in Engineering.

The three forces acting on the water tank represent the effect of the wind. Replace this system by a single resultant force and specify its vertical location from point O.

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A sign is subjected to a wind loading that exerts horizontal forces of 300 lb on joints B and C of one of the side supporting trusses. Determine the force in members BC, CD, DB, and DE of the truss and state whether the members are in tension or compression.

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Determine the force in members FF, FB, and BC of the Fink truss and indicate whether the members are in tension or compression.

A car is traveling along the circular curve of radius r = 300 ft. At the instant shown, its angular rate of rotation is = 0.4 rad / s, which is increasing at the rate of = 0.2 rad / s². Determine the magnitude of the velocity of the car at this instant.

A ball is thrown downward on the 30 inclined plane so that when it rebounds perpendicular to the incline it has a velocity of v_A = 40 ft/s. Determine the distance R where it strikes the plane at B.

The floor beams AB and BC are stiffened using the two tie rods CD and AD. Determine the force along each rod. Assume the three contacting members at B are smooth and the joints at A, C, and D are pins.

The Warren truss is used to support a staircase. Determine the force in members CE, ED, and DF, and state whether the members are in tension or compression. Assume all joints are pinned.

A race car starting from rest moves along a straight track with an acceleration as shown in the graph (where for t 10 s, a = 8 m/s²). Determine the time t for the car to reach a speed of 50 m/s.

A two-stage missile is fired vertically from rest with an acceleration as shown in the graph. In 15 s the first stage A burns out and the second stage B ignites. How fast is the rocket moving and how far has it gone at t = 20 s? How fast is the missile moving and how far has it gone at t = 20 s?

A 1.5-lb brick is released from rest A and slides down the inclined roof. If the coefficient of friction between the roof and the brick is = 0.3, determine the speed at which the brick strikes the gutter G.

Gear A is in mesh with gear B as shown. If A starts from rest and has a constant angular acceleration of _A = 2 rad/s², determine the tome needed for B to attain an angular velocity of _B = 50 rad/s.

A hockey puck is traveling to the left with a velocity of v₁ = 10 m/s when it is struck by a hockey stick and given a velocity of v₂ = 20 m/s as shown. Determine the magnitude of the net impulse exerted by the hockey stick on the puck. The puck has a mass of 0.2 kg.

A car is traveling at a speed of 80 ft/s when the brakes are suddenly applied, causing a constant deceleration of 10 ft/s². Determine the time required to stop the car and the distance traveled before stopping.

An electric train car, having a mass of 25 Mg, travels up a 10 incline with a constant speed of 80 km/h. Determine the power required to overcome the force of gravity.

A motor hoists a 50-kg crate at constant speed to a height of h = 6 m in 3 s. If the indicated power of the motor is 4 kw, determine the motor's efficiency.

A truck has a weight of 25,000 lb and an engine which transmits a power of 350hp. Assuming that the wheels do not slip on the ground, determine the angle of the largest incline the truck can climb at a constant speed of v = 50 ft/s.

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Determine the magnitude of the forces in pins B and D of the four-member frame.

The Pratt bridge truss is subjected to the loading shown. Determine the force in members CD, CL and ML, and indicate whether these members are in tension or compression.

The uniform slender rod has a mass of 5 kg. Determine the magnitude of the reaction at the pin O when the cord at A is cut and = 90

The elevator E and its freight have a total mass of 400 kg. Hoisting is provided by the motor M and the 60-kg block C. If the motor has an efficiency of e = 0.6, determine the power that must be supplied to the motor when the elevator is hoisted upward at a constant speed of v_E = m/s.

The refrigerator has a weight of 200 lb and a center of gravity at G. Determine the force P required to move it. Will the refrigerator tip or slip? Take = 0.4.

A 17-kg ladder has a center of mass at G. If the coefficients of friction at A and B are _A = 0.3 and _B = 0.2, respectively, determine the smallest horizontal force that the man must exert of the ladder at point C in order to push the ladder forward.

The wind has blown sand over a platform such that the intensity of load can be approximated by the function . Simplify this distributed loading to a single concentrated force and specify the magnitude and location of the force measured from A.

The hoist supports the 125-kg engine. Determine the force the load creates in member DB and in member FB, which contains the hydraulic cylinder H.

A motor supplies a constant torque or twist of M = 120 lb ft to the drum. If the drum has a weight of 30 lb and a radius of gyration of k₀ = 0.8ft, determine the speed of the 15-lb carte A after it rises s = 4 ft starting from rest. Neglect the weight of the cord.

Explore topic-wise MCQs in Engineering.

The three forces acting on the water tank represent the effect of the wind. Replace this system by a single resultant force and specify its vertical location from point O.

Determine the magnitude and direction of the couple moment.

Replace the loading by an equivalent force and couple moment acting at point O.

The bricks on top of the beam and the supports at the bottom create the distributed loading shown in the second figure. Determine the required intensity w and dimension d of the right support so that the resultant force and couple moment about point A of the system are both zero.

Determine the magnitude of the x and y components of the 700-lb force.

The cable AO exerts a force on the top of the pole of F = { 120i 90j 80k} lb. If the cable has a length of 34 ft, determine the height z of the pole and the location (x,y) of its base.

The cord is attached between two walls. If it is 8 m long, determine the distance x to the point of attachment at B.

The main beam along the wing of an airplane is swept back at an angle of 25 . From load calculations it is determined that the beam is subjected to couple moments aMx = 25,000 lb ft and My = 17,000 lb ft. Determine the equivalent couple moments created about the x' and y' axis.

The principles of a differential chain block are indicated schematically in the figure. Determine the magnitude of force P needed to support the 800-N force. Also compute the distance x where the cable must be attached to bar AB so the bar remains horizontal. All pulleys have a radius of 60 mm.

Compute the force in each member of the Warren truss and indicate whether the members are in tension or compression. All the members are 3 m long.

A sign is subjected to a wind loading that exerts horizontal forces of 300 lb on joints B and C of one of the side supporting trusses. Determine the force in members BC, CD, DB, and DE of the truss and state whether the members are in tension or compression.

A tower used in an electrical substation supports a power line which exerts a horizontal tension of T = 500 lb on each side truss of the tower as shown. Determine the force in members BC, CM, and LM of a side truss and indicate whether the members are in tension or compression.

Determine the force in members FF, FB, and BC of the Fink truss and indicate whether the members are in tension or compression.

A car is traveling along the circular curve of radius r = 300 ft. At the instant shown, its angular rate of rotation is = 0.4 rad / s, which is increasing at the rate of = 0.2 rad / s2. Determine the magnitude of the velocity of the car at this instant.

A ball is thrown downward on the 30 inclined plane so that when it rebounds perpendicular to the incline it has a velocity of vA = 40 ft/s. Determine the distance R where it strikes the plane at B.

The floor beams AB and BC are stiffened using the two tie rods CD and AD. Determine the force along each rod. Assume the three contacting members at B are smooth and the joints at A, C, and D are pins.

The Warren truss is used to support a staircase. Determine the force in members CE, ED, and DF, and state whether the members are in tension or compression. Assume all joints are pinned.

A race car starting from rest moves along a straight track with an acceleration as shown in the graph (where for t 10 s, a = 8 m/s2). Determine the time t for the car to reach a speed of 50 m/s.

A two-stage missile is fired vertically from rest with an acceleration as shown in the graph. In 15 s the first stage A burns out and the second stage B ignites. How fast is the rocket moving and how far has it gone at t = 20 s? How fast is the missile moving and how far has it gone at t = 20 s?

A 1.5-lb brick is released from rest A and slides down the inclined roof. If the coefficient of friction between the roof and the brick is = 0.3, determine the speed at which the brick strikes the gutter G.

Gear A is in mesh with gear B as shown. If A starts from rest and has a constant angular acceleration of A = 2 rad/s2, determine the tome needed for B to attain an angular velocity of B = 50 rad/s.

A hockey puck is traveling to the left with a velocity of v1 = 10 m/s when it is struck by a hockey stick and given a velocity of v2 = 20 m/s as shown. Determine the magnitude of the net impulse exerted by the hockey stick on the puck. The puck has a mass of 0.2 kg.

A car is traveling at a speed of 80 ft/s when the brakes are suddenly applied, causing a constant deceleration of 10 ft/s2. Determine the time required to stop the car and the distance traveled before stopping.

An electric train car, having a mass of 25 Mg, travels up a 10 incline with a constant speed of 80 km/h. Determine the power required to overcome the force of gravity.

A motor hoists a 50-kg crate at constant speed to a height of h = 6 m in 3 s. If the indicated power of the motor is 4 kw, determine the motor's efficiency.

A truck has a weight of 25,000 lb and an engine which transmits a power of 350hp. Assuming that the wheels do not slip on the ground, determine the angle of the largest incline the truck can climb at a constant speed of v = 50 ft/s.

A boy twirls a 15-lb bucket of water in a vertical circle. If the radius of curvature of the path is 4 ft, determine the minimum speed the bucket must have when it is overhead at A so no water spills out.

Determine the magnitude of the forces in pins B and D of the four-member frame.

The Pratt bridge truss is subjected to the loading shown. Determine the force in members CD, CL and ML, and indicate whether these members are in tension or compression.

The uniform slender rod has a mass of 5 kg. Determine the magnitude of the reaction at the pin O when the cord at A is cut and = 90

The elevator E and its freight have a total mass of 400 kg. Hoisting is provided by the motor M and the 60-kg block C. If the motor has an efficiency of e = 0.6, determine the power that must be supplied to the motor when the elevator is hoisted upward at a constant speed of vE = m/s.

The refrigerator has a weight of 200 lb and a center of gravity at G. Determine the force P required to move it. Will the refrigerator tip or slip? Take = 0.4.

A 17-kg ladder has a center of mass at G. If the coefficients of friction at A and B are A = 0.3 and B = 0.2, respectively, determine the smallest horizontal force that the man must exert of the ladder at point C in order to push the ladder forward.

The wind has blown sand over a platform such that the intensity of load can be approximated by the function . Simplify this distributed loading to a single concentrated force and specify the magnitude and location of the force measured from A.

The hoist supports the 125-kg engine. Determine the force the load creates in member DB and in member FB, which contains the hydraulic cylinder H.

A motor supplies a constant torque or twist of M = 120 lb ft to the drum. If the drum has a weight of 30 lb and a radius of gyration of k0 = 0.8ft, determine the speed of the 15-lb carte A after it rises s = 4 ft starting from rest. Neglect the weight of the cord.

The main beam along the wing of an airplane is swept back at an angle of 25 . From load calculations it is determined that the beam is subjected to couple moments aM_x = 25,000 lb ft and M_y = 17,000 lb ft. Determine the equivalent couple moments created about the x' and y' axis.

A car is traveling along the circular curve of radius r = 300 ft. At the instant shown, its angular rate of rotation is = 0.4 rad / s, which is increasing at the rate of = 0.2 rad / s². Determine the magnitude of the velocity of the car at this instant.

A ball is thrown downward on the 30 inclined plane so that when it rebounds perpendicular to the incline it has a velocity of v_A = 40 ft/s. Determine the distance R where it strikes the plane at B.

A race car starting from rest moves along a straight track with an acceleration as shown in the graph (where for t 10 s, a = 8 m/s²). Determine the time t for the car to reach a speed of 50 m/s.

Gear A is in mesh with gear B as shown. If A starts from rest and has a constant angular acceleration of _A = 2 rad/s², determine the tome needed for B to attain an angular velocity of _B = 50 rad/s.

A hockey puck is traveling to the left with a velocity of v₁ = 10 m/s when it is struck by a hockey stick and given a velocity of v₂ = 20 m/s as shown. Determine the magnitude of the net impulse exerted by the hockey stick on the puck. The puck has a mass of 0.2 kg.

A car is traveling at a speed of 80 ft/s when the brakes are suddenly applied, causing a constant deceleration of 10 ft/s². Determine the time required to stop the car and the distance traveled before stopping.

The elevator E and its freight have a total mass of 400 kg. Hoisting is provided by the motor M and the 60-kg block C. If the motor has an efficiency of e = 0.6, determine the power that must be supplied to the motor when the elevator is hoisted upward at a constant speed of v_E = m/s.

A 17-kg ladder has a center of mass at G. If the coefficients of friction at A and B are _A = 0.3 and _B = 0.2, respectively, determine the smallest horizontal force that the man must exert of the ladder at point C in order to push the ladder forward.

A motor supplies a constant torque or twist of M = 120 lb ft to the drum. If the drum has a weight of 30 lb and a radius of gyration of k₀ = 0.8ft, determine the speed of the 15-lb carte A after it rises s = 4 ft starting from rest. Neglect the weight of the cord.