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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 5251. |
The diagram shows a capacitor C and a resistor R connected in series to an ac source. \[{{V}_{1}}\] and \[{{V}_{2}}\] are voltmeters and A is an ammeter Consider now the following statements I. Readings in A and \[{{V}_{2}}\] are always in phaseII. Reading in \[{{V}_{1}}\] is ahead in phase with reading in\[{{V}_{2}}\]III. Readings in A and \[{{V}_{1}}\] are always in phase which of these statements are/is correct |
| A. | I only |
| B. | II only |
| C. | I and II only |
| D. | II and III only |
| Answer» C. I and II only | |
| 5252. |
A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be |
| A. | Halved |
| B. | The same |
| C. | Doubled |
| D. | Quadrupled |
| Answer» C. Doubled | |
| 5253. |
A typical light dimmer used to dim the stage lights in a theatre consists of a variable induction for L (where inductance is adjustable between zero and\[{{L}_{\max }}\] connected in series with a light bulb B as shown. The mains electrical supply is 220 V a 50 Hz, the light bulb is rated at 220 V, 1100 W. What \[{{L}_{\max }}\]is required if the rate of energy dissipation in to mains the light bulb is to be varied by a factor of 5 from its upper limit of 1100W? |
| A. | 0.69 H |
| B. | 0.28 H |
| C. | 0.38 H |
| D. | 0.56 H |
| Answer» C. 0.38 H | |
| 5254. |
Plane figures made of thin wires of resistance R = 50 milli ohm/metre are located in a uniform magnetic field perpendicular into the plane of the figures and which decrease at the rate dB/dt= 0.1 mT/s. Then currents in the inner and outer boundary are. (The inner radius a = 10 cm and outer radius b = 20 cm) |
| A. | \[{{10}^{-4}}A\](Clockwise), \[2\times {{10}^{-4}}\,A\](Clockwise) |
| B. | \[{{10}^{-4}}A\](Anticlockwise),\[2\times {{10}^{-4}}\,A\](Clockwise) |
| C. | \[2\times {{10}^{-4}}\,A\](clockwise),\[{{10}^{-4}}\,A\](anticlockwise) |
| D. | \[2\times {{10}^{-4}}\,A\](anticlockwise),\[{{10}^{-4}}A\](anticlockwise) |
| Answer» B. \[{{10}^{-4}}A\](Anticlockwise),\[2\times {{10}^{-4}}\,A\](Clockwise) | |
| 5255. |
PQ is an infinite current carrying conductor. AB and CD are smooth conducting rods on which a conductor EF moves with constant velocity v as shown. The force needed to maintain constant speed of EF is. |
| A. | \[\frac{1}{vR}{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\] |
| B. | \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\frac{1}{vR}\] |
| C. | \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\frac{v}{R}\] |
| D. | \[\frac{v}{R}{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\] |
| Answer» B. \[{{\left[ \frac{{{\mu }_{0}}Iv}{2\pi }In\left( \frac{b}{a} \right) \right]}^{2}}\frac{1}{vR}\] | |
| 5256. |
A horizontal ring of radius \[r=1/2m\] is kept in a vertical constant magnetic field 1 T. The ring is collapsed from maximum area to zero area in 1 s. Then the emf induced in the ring is |
| A. | \[1\,V\] |
| B. | \[(\pi /4)\,V\] |
| C. | \[(\pi /2)\,V\] |
| D. | \[\pi \,V\] |
| Answer» C. \[(\pi /2)\,V\] | |
| 5257. |
The self-inductance of a choke coil is 10 mH. When it is connected with a 10 V dc source, then the loss of power is 20 watt. When it is connected with 10 volt ac source loss of power is 10 watt. The frequency of ac source will be |
| A. | 50 Hz |
| B. | 60 Hz |
| C. | 80 Hz |
| D. | 100 Hz |
| Answer» D. 100 Hz | |
| 5258. |
A wire is sliding as shown in figure. The angle between the acceleration and the velocity of the wire is |
| A. | \[30{}^\circ \] |
| B. | \[40{}^\circ \] |
| C. | \[120{}^\circ \] |
| D. | \[90{}^\circ \] |
| Answer» D. \[90{}^\circ \] | |
| 5259. |
A resistance of 20\[\Omega \] is connected to a source of an alternating potential V= 220\[\sin (100\pi t)\]. The time taken by the current to change from the peak value to rms value, is |
| A. | \[0.2\,s\] |
| B. | \[0.25\,s\] |
| C. | \[0.25\times {{10}^{-3}}\,s\] |
| D. | \[0.25\times {{10}^{-3}}\,s\] |
| Answer» E. | |
| 5260. |
A metal conductor of length 1 m rotates vertically about one of its ends at an angular velocity 5 radians per second. If the horizontal component of the earth's magnetic field is\[0.2\times {{10}^{-4}}T\], then the emf developed between the two ends of the conductor is |
| A. | \[5\,\mu V\] |
| B. | \[50\,\mu V\] |
| C. | \[5\,mV\] |
| D. | \[50\,mV\] |
| Answer» C. \[5\,mV\] | |
| 5261. |
A 300\[\Omega \]. resistor is connected in series with a parallel-plate capacitor across the terminals of a 50.0 Hz ac generator. When the gap between the plates is empty, its capacitance is\[70/22\mu F\]. The ratio of the rms current in the circuit when the capacitor is empty to that when ruby mica of dielectric constant k = 5.0 is inserted between the plates, is equal to |
| A. | 0.1 |
| B. | 0.3 |
| C. | 0.6 |
| D. | 2.9 |
| Answer» C. 0.6 | |
| 5262. |
A fully charged capacitor C with initial charge \[{{q}_{0}}\] is connected to a coil of self-inductance L at t = 0. The time at which the energy is stored equally between the electric and the magnetic fields is |
| A. | \[\pi \sqrt{LC}\] |
| B. | \[\frac{\pi }{4}\sqrt{LC}\] |
| C. | \[2\pi \sqrt{LC}\] |
| D. | \[\sqrt{LC}\] |
| Answer» C. \[2\pi \sqrt{LC}\] | |
| 5263. |
A coil of inductance 300 mH and resistance 2\[\Omega \]. is connected to a source of voltage 2 V. The current reaches half of its steady state value in |
| A. | 0.3s |
| B. | 0.15s |
| C. | 0.1 s |
| D. | 0.05s |
| Answer» D. 0.05s | |
| 5264. |
A thin semicircular conducting ring of radius R is fallin with its plane vertical in a horizontal magnetic induction B. At the position MNQ, the speed of the ring is v and the potential difference developed across the ring is |
| A. | Zero |
| B. | \[Bv\pi {{R}^{2}}/2\] and M is at higher potential |
| C. | \[\pi RBv\]and Q is at higher potential |
| D. | \[2RBv\]and Q is at higher potential |
| Answer» E. | |
| 5265. |
A circular disc x of radius \[R\] is made from an iron plate of thickness \[t\], and another disc \[Y\] of radius 4\[R\] is made from an iron plate of thickness \[t\]/4. Then the relation between the moment of inertia \[{{I}_{x\,}}\,and\,{{I}_{Y}}\]is |
| A. | \[{{I}_{Y}}=64{{I}_{X}}\] |
| B. | \[{{I}_{Y}}=32{{I}_{X}}\] |
| C. | \[{{I}_{Y}}=16{{I}_{X}}\] |
| D. | \[{{I}_{Y}}={{I}_{X}}\] |
| Answer» B. \[{{I}_{Y}}=32{{I}_{X}}\] | |
| 5266. |
A thick walled hollow sphere has outer radius \[R\]. It rolls down an inclined plane without slipping and its speed at the bottom is\[v\]. If the inclined plane is frictionless and the sphere slides down without rolling, its speed at the bottom is \[5v/4\]. What is the radius of gyration of the sphere? |
| A. | \[\frac{R}{\sqrt{2}}\] |
| B. | \[\frac{R}{2}\] |
| C. | \[\frac{3R}{4}\] |
| D. | \[\frac{\sqrt{3}R}{4}\] |
| Answer» D. \[\frac{\sqrt{3}R}{4}\] | |
| 5267. |
A hoop rolls on a horizontal ground without Slipping with linear speed \[v\]. Speed of a particle \[P\] on the circumference of the hoop at angle \[\theta \] is |
| A. | \[2v\,\sin \,(\theta /2)\] |
| B. | \[v\,\sin \,\theta \] |
| C. | \[2v\,\cos \,(\theta /2)\] |
| D. | \[v\,\cos \,\theta \] |
| Answer» B. \[v\,\sin \,\theta \] | |
| 5268. |
A thin wire of length \[L\] and uniform linear mass density \[\rho \] is bent into a circular loop with centre at O as shown. The moment of inertia of the loop about an axis XY is |
| A. | \[\frac{\rho {{L}^{3}}}{8{{\pi }^{2}}}\] |
| B. | \[\frac{\rho {{L}^{3}}}{16{{\pi }^{2}}}\] |
| C. | \[\frac{5\rho {{L}^{3}}}{8{{\pi }^{2}}}\] |
| D. | \[\frac{3\rho {{L}^{3}}}{8{{\pi }^{2}}}\] |
| Answer» E. | |
| 5269. |
Two points of a rod move with velocities 3\[v\] and perpendicular to the rod and in the same direction, separated by a distance 'r'. Then the angular velocity of the rod is |
| A. | \[\frac{3v}{r}\] |
| B. | \[\frac{4v}{r}\] |
| C. | \[\frac{5v}{r}\] |
| D. | \[\frac{2v}{r}\] |
| Answer» E. | |
| 5270. |
Which of the following has the highest moment of inertia when each of them has the same mass and the same radius? |
| A. | A ring about any of its diameter |
| B. | A disc about any of its diameter |
| C. | A hollow sphere about any of its diameter |
| D. | A solid sphere about any of its diameter |
| Answer» D. A solid sphere about any of its diameter | |
| 5271. |
A pulley of radius 2 m is rotated about its axis by a force \[F=(20t-5{{t}^{2}})\] newton (where \[t\] is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is \[10\,kg{{m}^{2}}\], the number of rotations made by the pulley before its direction of motion is reversed, is: |
| A. | less than 3 |
| B. | more than 3 but less than 6 |
| C. | more than 6 but less than 9 |
| D. | more than 9 |
| Answer» C. more than 6 but less than 9 | |
| 5272. |
Consider a uniform square plate of side \[a\] and mass \[M\]. The moment of inertia of this plate about an axis perpendicular to its plane and passing through one of its comers is |
| A. | \[\frac{5}{6}M{{a}^{2}}\] |
| B. | \[\frac{1}{12}M{{a}^{2}}\] |
| C. | \[\frac{7}{12}M{{a}^{2}}\] |
| D. | \[\frac{2}{3}M{{a}^{2}}\] |
| Answer» E. | |
| 5273. |
A uniform rod of length \[L\] (in between the supports) and mass \[m\] is placed on two supports \[A\] and \[B\]. The rod breaks suddenly at length \[L/10\] from the support B. Find the reaction at support A immediately after the rod breaks. |
| A. | \[\frac{9}{40}mg\] |
| B. | \[\frac{19}{40}mg\] |
| C. | \[\frac{mg}{2}\] |
| D. | \[\frac{9}{20}mg\] |
| Answer» B. \[\frac{19}{40}mg\] | |
| 5274. |
A small solid sphere of radius \[r\] rolls down an incline without slipping which ends into a vertical loop of radius \[R\]. Find the height above the base so that it just loops the loop |
| A. | \[\frac{5}{2}R\] |
| B. | \[\frac{5}{2}(R-r)\] |
| C. | \[\frac{25}{10}(R-r)\] |
| D. | \[\frac{27}{10}R-\frac{17r}{10}\] |
| Answer» E. | |
| 5275. |
A body is rolling without slipping on a horizontal plane. The rotational energy of the body is 40% of the total kinetic energy. Identify the body. |
| A. | Ring |
| B. | Hollow cylinder |
| C. | Solid cylinder |
| D. | Hollow sphere |
| Answer» E. | |
| 5276. |
A particle is moving along a line \[y=x+a\] with a constant velocity \[v\]. Find the angular momentum of the particle about the origin. |
| A. | \[mva\] |
| B. | \[mva\sqrt{2}\] |
| C. | \[\frac{mva}{\sqrt{2}}\] |
| D. | \[\frac{mvy}{x\sqrt{2}}\] |
| Answer» D. \[\frac{mvy}{x\sqrt{2}}\] | |
| 5277. |
Two points of a rod move with velocities \[3v\] and \[v\] perpendicular to the rod and in the same direction separated by a distance '\[r\]'. The angular velocity of the rod is |
| A. | \[\frac{3v}{r}\] |
| B. | \[\frac{4v}{r}\] |
| C. | \[\frac{5v}{r}\] |
| D. | \[\frac{2v}{r}\] |
| Answer» E. | |
| 5278. |
A uniform disc of mass \[M\] and radius \[R\] is mounted on an axle supported in frictionless bearings. A light cord is wrapped around the rim of the disc and a steady downward pull \[T\] is exerted on the cord. The angular acceleration of the disc is |
| A. | \[\frac{T}{MR}\] |
| B. | \[\frac{MR}{T}\] |
| C. | \[\frac{2T}{MR}\] |
| D. | \[\frac{MR}{2T}\] |
| Answer» D. \[\frac{MR}{2T}\] | |
| 5279. |
A horizontal heavy uniform bar of weight \[W\] is supported at its ends by two men. At the instant, one of the men lets go off his end of the rod, the other feels the force on his hand changed to |
| A. | \[W\] |
| B. | \[\frac{W}{2}\] |
| C. | \[\frac{3W}{4}\] |
| D. | \[\frac{W}{4}\] |
| Answer» E. | |
| 5280. |
A cube of side \[a\] is placed on an inclined plane of inclination \[\theta \]. What is the maximum value of 9 for which the cube will not topple? |
| A. | \[15{}^\circ \] |
| B. | \[30{}^\circ \] |
| C. | \[45{}^\circ \] |
| D. | \[69{}^\circ \] |
| Answer» D. \[69{}^\circ \] | |
| 5281. |
Three identical thin rods, each of length \[L\] and mass m, are welded perpendicular to one another as shown in figure. The assembly is rotated about an axis that passes through the end of one rod and is parallel to another. The moment of inertia of this structure about this axis is |
| A. | \[\frac{7}{12}m{{L}^{2}}\] |
| B. | \[\frac{11}{14}m{{L}^{2}}\] |
| C. | \[\frac{5}{15}m{{L}^{2}}\] |
| D. | \[\frac{11}{12}m{{L}^{2}}\] |
| Answer» E. | |
| 5282. |
For the arrangement shown in figure, the switch is closed at t = 0. The time after which the current becomes \[2.5\mu A\]is given by (take ln2 = 0.69) |
| A. | 10 s |
| B. | 5 s |
| C. | 7 s |
| D. | 0.693 s |
| Answer» D. 0.693 s | |
| 5283. |
Find the equivalent resistance. across the terminals of source of e.m.f. 24 V for the circuit shown in figure |
| A. | \[15\Omega \] |
| B. | \[10\Omega \] |
| C. | \[5\Omega \] |
| D. | \[4\Omega \] |
| Answer» D. \[4\Omega \] | |
| 5284. |
A network of twelve resistances each of resistance R form a square of squares as shown in the figure. The outer square is fitted in a metal ring of negligible resistance. Find the resistance between centre of the square and the ring. |
| A. | R/4 |
| B. | R/2 |
| C. | 3R/8 |
| D. | R/12 |
| Answer» D. R/12 | |
| 5285. |
The plot represents the flow of current through a wire at three different times. The ratio of charges flowing through the wire at different times is (see figure) |
| A. | 2 : 1 : 2 |
| B. | 0.0437847222222222 |
| C. | 0.0423726851851852 |
| D. | 0.085462962962963 |
| Answer» D. 0.085462962962963 | |
| 5286. |
Find the equivalent resistance between A and B. Each resistor has same resistance R. |
| A. | \[\frac{8}{5}R\] |
| B. | \[\frac{6}{5}R\] |
| C. | \[\frac{7}{5}R\] |
| D. | \[\frac{4}{5}R\] |
| Answer» E. | |
| 5287. |
A wire of cross-section area A, length \[{{L}_{1}}\] resistivity \[{{\rho }_{1}}\] and temperature coefficient of resistivity \[{{\alpha }_{1}}\] is connected in series to a second wire of length \[{{L}_{2}}\] resistivity \[{{\rho }_{2}}\], temperature coefficient of resistivity \[{{\alpha }_{2}}\]and the same are A, so that wires carry same current. Total resistance R is independent of temperature for small temperature change if (Thermal expansion effect is negligible) |
| A. | \[{{\alpha }_{1}}=\,-{{\alpha }_{2}}\] |
| B. | \[{{\rho }_{1}}{{L}_{1}}{{\alpha }_{1}}+{{\rho }_{2}}{{L}_{2}}{{\alpha }_{2}}=0\] |
| C. | \[{{L}_{1}}{{\alpha }_{1}}+{{L}_{2}}{{\alpha }_{2}}=0\] |
| D. | None of these |
| Answer» C. \[{{L}_{1}}{{\alpha }_{1}}+{{L}_{2}}{{\alpha }_{2}}=0\] | |
| 5288. |
For comparing the e.m.f.'s of two cells with a potentiometer, a standard cell is used to develop a potential gradient along the wires. Which of the following possibilities would make the experiment unsuccessful? |
| A. | The e.m.f. of the standard cell is larger than the E e.m.f.'s of the two cells |
| B. | The diameter of the wires is the same and uniform throughout |
| C. | The number of wires is ten |
| D. | The e.m.f. of the standard cell is smaller than the e.m.f.'s of the two cells |
| Answer» E. | |
| 5289. |
Two wires each of radius of cross section r but of different materials are connected together end to end (i.e. in series). If the densities of charge carriers in the two wires are in the ratio 1:4, the drift velocity of electrons in the two wires will be in the ratio |
| A. | 1 : 2 |
| B. | 0.0840277777777778 |
| C. | 4 : 1 |
| D. | 0.0444444444444444 |
| Answer» D. 0.0444444444444444 | |
| 5290. |
The temperature coefficient of resistance of conductor varies as\[\alpha (T)=3{{T}^{2}}+2T\]. If \[{{R}_{0}}\] is resistance at T= 0 and R is resistance at T, then |
| A. | \[R={{R}_{0}}(6T+2)\] |
| B. | \[R=2{{R}_{0}}(3+2T)\] |
| C. | \[R={{R}_{0}}(1+{{T}^{2}}+{{T}^{3}})\] |
| D. | \[R={{R}_{0}}(1-T+{{T}^{2}}+{{T}^{3}})\] |
| Answer» D. \[R={{R}_{0}}(1-T+{{T}^{2}}+{{T}^{3}})\] | |
| 5291. |
A battery of emf \[{{E}_{0}}=12\,V\] is connected across a 4 m long uniform wire having resistance \[\frac{4\Omega }{m}\] the cells of small m emfs \[{{\varepsilon }_{1}}=2\,V\] and \[{{\varepsilon }_{2}}=4\,V\] having internal resistance 2\[\Omega \] and 6\[\Omega \] respectively, are connected as shown in the figure. If galvanometer shows no deflection at the point N, the distance of point N from the point A is equal to |
| A. | \[\frac{1}{6}m\] |
| B. | \[\frac{1}{3}m\] |
| C. | \[25m\] |
| D. | \[50m\] |
| Answer» D. \[50m\] | |
| 5292. |
The effective resistance between points P and Q of the electrical circuit shown in the figure is |
| A. | \[2Rr/(R+r)\] |
| B. | \[8R(R+r)(3R+r)\] |
| C. | \[2r+4R\] |
| D. | \[5R/2+2r\] |
| Answer» B. \[8R(R+r)(3R+r)\] | |
| 5293. |
For a cell, a graph is plotted between the potential Difference V across the terminals of the cell and the current \[I\] drawn from the cell (see figure). The emf and the internal resistance of the cell are E and r respectively. Then |
| A. | \[E=2V,\,r=0.5\,\Omega \] |
| B. | \[E=2V,\,r=0.4\,\Omega \] |
| C. | \[E>2V,\,r=0.5\,\Omega \] |
| D. | \[E>2V,\,r=0.4\,\Omega \] |
| Answer» C. \[E>2V,\,r=0.5\,\Omega \] | |
| 5294. |
When 5V potential difference is applied across a wire of length 0.1 m, the drift speed of electrons is \[2.5\times {{10}^{-4}}m{{s}^{-1}}\] If the electron density in the wire is \[8\times {{10}^{28}}{{m}^{-3}}s\], the resistivity of the material is close to |
| A. | \[1.6\times {{10}^{-8}}\Omega \,m\] |
| B. | \[1.6\times {{10}^{-7}}\Omega \,m\] |
| C. | \[1.6\times {{10}^{-6}}\Omega \,m\] |
| D. | \[1.6\times {{10}^{-5}}\Omega \,m\] |
| Answer» E. | |
| 5295. |
A resistor 'R' and \[2\,\mu F\] capacitor in series is connected through a switch to 200 V direct supply. Across the capacitor is a neon bulb that lights up at 120 V. Calculate the value of R to make the bulb light up 5 s after the switch has been closed. \[(lo{{g}_{10}}2.5=0.4)\] |
| A. | \[1.3\times {{10}^{4}}\Omega \] |
| B. | \[1.7\times {{10}^{5}}\Omega \] |
| C. | \[2.7\times {{10}^{6}}\Omega \] |
| D. | \[3.3\times {{10}^{7}}\Omega \] |
| Answer» D. \[3.3\times {{10}^{7}}\Omega \] | |
| 5296. |
In order to determine the e.m.f. of a storage battery it was connected in series with a standard cell (both are adding) in a certain circuit and a current \[{{I}_{1}}\] was obtained. When polarity of the standard cell is reversed, a current \[{{I}_{2}}\] was obtained in the same direction as that of \[{{I}_{1}}\] what is the e.m.f. \[{{\varepsilon }_{1}}\] of the storage battery? The e.m.f. of the standard cell is\[{{\varepsilon }_{2}}\]. |
| A. | \[{{\varepsilon }_{1}}=\frac{{{I}_{1}}+{{I}_{2}}}{{{I}_{1}}-{{I}_{2}}}{{\varepsilon }_{2}}\] |
| B. | \[{{\varepsilon }_{1}}=\frac{{{I}_{1}}+{{I}_{2}}}{{{I}_{2}}-{{I}_{1}}}{{\varepsilon }_{2}}\] |
| C. | \[{{\varepsilon }_{1}}=\frac{{{I}_{1}}-{{I}_{2}}}{{{I}_{1}}+{{I}_{2}}}{{\varepsilon }_{2}}\] |
| D. | \[{{\varepsilon }_{1}}=\frac{{{I}_{2}}-{{I}_{1}}}{{{I}_{1}}+{{I}_{2}}}{{\varepsilon }_{2}}\] |
| Answer» B. \[{{\varepsilon }_{1}}=\frac{{{I}_{1}}+{{I}_{2}}}{{{I}_{2}}-{{I}_{1}}}{{\varepsilon }_{2}}\] | |
| 5297. |
The n rows each containing m cells in series are joined in parallel. Maximum current is taken from this combination across an external resistance of\[3\Omega \] resistance. If the total number of cells used are 24 and internal resistance of each cell is 0.5 \[\Omega \] then |
| A. | \[m=8,\,n=3\] |
| B. | \[m=6,\,n=4\] |
| C. | \[m=12,\,n=2\] |
| D. | \[m=2,\,n=12\] |
| Answer» D. \[m=2,\,n=12\] | |
| 5298. |
The velocities of two particles \[A\] and \[B\] of same mass are \[{{\vec{V}}_{A}}=a\vec{i}\,and\,{{\vec{V}}_{B}}=b\hat{j}\] where a and b are constants. The acceleration of particle\[A\] is \[(2a\hat{i}+4b\hat{j})\] and acceleration of particle \[B\] is \[(a\hat{i}-4b\hat{j})\] (in \[m/{{s}^{2}}\]). The centre of mass of two particle will move in |
| A. | straight line |
| B. | parabola |
| C. | ellipse |
| D. | circle |
| Answer» B. parabola | |
| 5299. |
In a gravity free space, a man of mass \[M\] standing at a height \[h\] above the floor, throws a ball of mass m straight down with a speed \[u\]. When the ball reaches the floor, the distance of the man above the floor will be |
| A. | \[h(1+m/M)\] |
| B. | \[h(2-m/M)\] |
| C. | \[2h\] |
| D. | a function of \[m\], \[M\], \[h\] and \[u\] |
| Answer» B. \[h(2-m/M)\] | |
| 5300. |
The centre of mass of a non-uniform rod of length \[L\] whose mass per unit length \[\lambda \] varies as \[\lambda =\frac{k.{{x}^{2}}}{L}\]where k is a constant and x is the distance of any point on rod from its one end, is (from the same end) |
| A. | \[\frac{3}{4}L\] |
| B. | \[\frac{1}{4}L\] |
| C. | \[\frac{k}{L}\] |
| D. | \[\frac{3k}{L}\] |
| Answer» B. \[\frac{1}{4}L\] | |