A body having 7 kg of mass moves slowly and covers a vertical height of 14 m. What is the work done in Joules and what force causes this work? Take g = 10 m/s2.

980, force acting opposite to gravity

1000, force acting opposite to gravity

A projectile has both change in kinetic and potential energy. Still the work done calculated between any two points is zero. This is due to _________

The displacement being in both vertical and horizontal directions

Inter-conversion of kinetic and potential energies

It moves with a positive acceleration

It moves with a very high velocity

It moves on an equipotential surface

It moves with a positive acceleration

It moves for some time, then rests, then moves again

It moves with a decreasing velocity

Total work done added with frictional losses

1.	A body moving with a constant velocity on normal ground initially has an energy of 1000 J. If the final energy is 800 J, what is the work done and which force causes this work?
A.	200 J, gravity
B.	-200 J, friction
C.	200 J, friction
D.	-200 J, gravity
Answer» C. 200 J, friction

2.	A body of mass 2 Kg, initially at rest, moves under the influence of an external force of magnitude 4 N on plane ground. What is the work done by the force and the change in kinetic energy in the first 10 seconds?
A.	400 J, 400 J
B.	-400 J, 400 J
C.	400 J, -400 J
D.	-400 J, -400 J
Answer» B. -400 J, 400 J

3.	The total energy of a system moving under the action of a conservative force changes by 50 J. Which of the following statements are correct with regards to the amount of work done?
A.	Amount of work done = 50 J
B.	Amount of work done < 50 J
C.	Amount of work done > 50 J
D.	Amount of work done <= 50 J
Answer» B. Amount of work done < 50 J

4.	A body having 7 kg of mass moves slowly and covers a vertical height of 14 m. What is the work done in Joules and what force causes this work? Take g = 10 m/s2.
A.	980, gravity
B.	980, force acting opposite to gravity
C.	1000, gravity
D.	1000, force acting opposite to gravity
Answer» B. 980, force acting opposite to gravity

5.	A projectile has both change in kinetic and potential energy. Still the work done calculated between any two points is zero. This is due to _________
A.	Presence of no external force
B.	No displacement
C.	The displacement being in both vertical and horizontal directions
D.	Inter-conversion of kinetic and potential energies
Answer» E.

6.	A body having 7 kg of mass moves with a velocity of 20 m/s covers a vertical height of 8.75 m. What is the work done by the moving force in Joules? Take g = 10 m/s2.
A.	0
B.	10
C.	15
D.	20
Answer» B. 10

7.	The change in the total energy of a body moving because of work being done on it is attributed by the change in kinetic energy only when ______
A.	It moves extremely slowly
B.	It moves with a very high velocity
C.	It moves on an equipotential surface
D.	It moves with a positive acceleration
Answer» D. It moves with a positive acceleration

8.	The total energy change of a body which covers a vertical height is constituted completely by the potential energy change only when ______
A.	It moves slowly
B.	It moves quickly
C.	It moves for some time, then rests, then moves again
D.	It moves with a decreasing velocity
Answer» B. It moves quickly

9.	The work done by a body while covering a vertical height of 5m is 50 kJ. By how much amount has the energy of the body changed?
A.	50 kJ
B.	-50 kJ
C.	25 kJ
D.	10 kJ
Answer» B. -50 kJ

10.	According to the work-energy theorem, total change in energy is equal to the _______
A.	Total work done
B.	Half of the total work done
C.	Total work done added with frictional losses
D.	Square of the total work done
Answer» B. Half of the total work done