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1. Multiple Choice Questions, (with One Correct Answer), , dy ois a, Also for CBSE PMT (Preliminary), AIEEE, AllIMS,, AFMC, DCE, OPMT, CPMT, BHU and All Other, Competitive as well as Board Examinations, , , , seat, , , , ba heared i : ye, , 1. A light and a heavy body have equal momentum,, Which one has greater KLE. ?, , (a) The light body (b) Both have equal K.E., (c) The heavy body (d) Data given is incomplete., 2. A bullet weighing 5 gm and moving with a velocity, 600 m/s strikes a § kg block of ice resting on a, frictionless surface. The speed of the block after, the collision is, (a) 6 emis (b) 60 cms, (c) 6 mys (d) 0-6 cms., 3, , |. Two masses of 1 pm and of 4 gm are moving with, equal linear momenta. The ratio of their kinetic, , energies is, (a) 4:1 (b) v1, (e) 1:2 (d) 1:16, , 4. Ifthe linear momentum is increased by 50%, then, K.E. will be increased by:, , (a) 50 % (b) 100 %, {c) 125 % (d)25 %, 5. When the K.E. ofa body is increased by 300 %, the, momentum of the body is increased by, (a) 20% (b) 50 %, (c) 100 % (d) 200 %., 6. Two bodies of masses mj, und m, have equal K.E., Their momenta shall be in the ratio of, (a) my: Mm, (b) mgs my, (©) Vin, Viti (a) ving: vim, 7. When a U-238 nucleus originally at rest, decays, , by emitting an «-particle say with a speed of Vm/s.,, the recoil speed (in m/s) of the residual nucleus is, , (a) Vi4 (b)-4 V/238, (c)-4.V/234 (d) 4 V/238, 8. A body of mass 2 kg is initially at rest. A constant, , force of 5 N acts on it for 10 sec. Then the average., power of the force is, , , , (a) 62-5 watt (b) 125 watt, (c) 50 watt {d) 25 watt., , 9, An electric motor creates a tension of 4500 N In», hoisting cable and reels it at the rate of 2m/s., What is the power of the electric motor ?, , (a) 15 kW (6) 9kW, (c) 225 W (d) 900 HP, , 10. A body of mass 2 kg Is projected vertically upwards with a speed of 3 m/s. The maximum, gravitational potential energy of the body is, (a) 183 (6) 4-53, ()95 (d) 2:25 J., , 11, A ball of mass 50 ¢ is thrown upwards, It rises to, a maximum height of 100 m, At what height its, , K.E. will be reduced to 70% ?, (a)30m (6) 40m, (c) 60m (d) 70 m., , 12. Arod of mass m and length / is lying on a horizontal table. Work done in making it stand on one, end will be, , (a)mgl (b) mg li2, (c) img hi4 (d)2mel, , 13, A light and a heavy body have equal K.E. Which, one has greater momentum ?, , (a) The heavy body (b) The light body, (c) Both have equal momentum, (d) Data is incomplete., 14. A bullet of mass a and velocity b is fired into a, large block of muss c. The final velocity of the, , , , system is, Os Oar, (c) (exh) .a (d) ae .b, , 15. A long spring is streched by 2 cm, Its potential (¢!, energy is V. Ifthe spring is stretched by 10cm, its 9, , potential energy would be ", (a) V25 (b) VIS 5, (c)5V ), , 0, , (d)25V ,, , 16. An engine develops 10 kW of power. How much, time will it take to lift a mass of 200 kg to a height |b, , of 40 m (g = 10 ms™?) '

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17,, , 18,, , 19., , 20,, , 21., , 22., , L ‘The vectors F = a7 +aj+ 3kand, a ax, , , , (a) dy, , (b) 5s, (c)& (d) 10s., A ball is dropped on the ground from 1 height of, Im. The ©, , efficient of restitution is 0-6. The, height to which the ball will rebound is, , (2) 0-6m (04m, , (c) 0-36 m (d) 0-16 m., , A force (mv? /r) is acting on a body of mass m, moving with a velocity v in a circle of radius r., , What is the work done by the force in moving the, body over half the circumference of the circle ?, , 2, m, @) > xar, , , , (6) Zero., , 2 2, () dy), 2 (@) ad, , A body constrained to move in y-direction is subjected to a force given byF =(-27 41574 6h), N. What is the work done by this force in moving, the body through a distance of 10m along y-axis ?, , (a) 1907 (6) 1603, , (c) 1503 (a) 205., , WK = si+ 77 - 3% ona ib = 274+ 27 - ck ore, perpendicular vectors, the value of c is, , (a) -2 (6)8, , (c) -7 (d) -8., , Angle that the vector A = 27 + 39 makes with yaxis is, , (a) tan—! 3/2) (b) tan=! (273), , (c) sin! (273) (d) cos™! (3 72)., , Two vectors A and B are such that, , [A+B] =| A-B |. Then angle between the, vectors A and B is, , (a) 0° (b) 60°, (c) 90° (d) 180°., (M.N.A,), , ‘The angle between the two vectors,, (- 27 +39 +28) and (i +2j-4k)is, (a) 0° (6) 90°, (c) 180° (d) None,, , (C.B.S.E. P.M.T.), , 6 =ai-2j~-k are perpendicular to each, other. The positive value of a is, , (a)3 (b)2, , 25,, , 27., , 28., , 29., , OE, , 32., , (dj), (EAM.C.ET. 1994), , i veloclty, cle moves with, “a km/ sander the influence of y, , Peb6i-4j+ * oe 10i 4 1S) ~ SK. The tnstan,, , constant foree,, ae power applied to the particle ts, (by) 45 isn!, , -1, (a) 35 Js (d) \o5I/s, , (c) 255758, (C.B.8.E. P.M.T, 2000), , What can be the angle between (A + #) ana, K-e, (a) 0° only, (c) 180° only ., Consider two observers moving a — to, , taspeed v along a straight line, They, eae nr mass m moving « distance lon, a rough surface. The following quantities will be, same as olserved by the two observers, , (a) work done by friction, , (b) acceleration of the block, , (c) kinetic energy of the block at timer, (d) total work done on the block,, , Work done is represented by, , (a) W= Px (b)W=?xF, () Wei x? (d)W=-3.F, , A body has its centre of mass at the origin. The, x-coordinates of the particles may be, , (a) positive for some cases and negative in other, cases, , (b) all positive, (c) all negative, , {e)!, , (b) 90” only, (d) between O° to 180°,, , (d) all non-negative,, , |. Fast neutrons can easily be slowed down by, , (a) the use of lead shield, , (b) passing them through water, , (c) Elastic collision with heavy nuclei, (¢) Applying a strong electric field,, , A particle moves along the x-axis from x = 0 to, += Sm under the influence of a force given by, F=7~ 2x4 327, Work done in the process is, (a) 70 (b) 270, , (ce) 35 (d) 135., , A shell is fired from a cannon with velocity, um /s atan angle # with the horizontal direction., At the highest point in its path, it explodes into 2, pieces of equal mass. One of the pieces retraces

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a, , ¥, , 35., , 37., , 39., , , , its path to the cannon. The speed in mys of the, , other piece immediately after the explosion is, (a) 3 cos@ (6) 20 case, (c) G72)» cose (4) (V3 2) uv cos@, , . If g is acceleration due to gravity on earth's sur, face, the gain in potential energy of an obj, , vet, mass m raised from surface of earth to a hed :, equal to radius R of the earth is :, , (a) (1/2) mgR (b) ImgR, (c)imgR (d) (174) mgR, , . Auniform chain of length L and mass M is lying, , on a smooth table and one third of its |, , th is, hanging vertically down over the edge siutain, If g is acceleration due to gravity, the work required to pull the hanging part on to the table is, (2) Mg (6) Mg L/3, (c) Mg Ly (d) Mg L/18, The KE. acquired by a mass m in travelling a, certain distance d, starting from rest, under the, action of a constant force is directly proportional, to, , (a)m (6) viv, (d) none of the above,, , (C.B.S.E,), , oe, , . A body, constrained to move in they direction, is, , subject toa force Fe (- 2i + 15] + 6k) N. What, is the work done by this force in moving the body, through a distance of 10 m along the y-axis ?, , (a) 20] (b) 1503, , (c) 160] (d) 1905. (C.P.M.T.), Consider a car moving along a straight horizontal, road with a speed of 72 km/h. If the coefficient of, static friction between road and tyres is 0-5, the, shortest distance in which the car can he stopped, is, , (a) 30m (6) 40m, (c)72m (d) 20m., f (Pre-Medical Dental), , . Out of a pair of identical springs of spring con, stant 240 N/m, one is compressed by 10 em and, the other is stretched by 10 em. The difference in, potential energy stored in the two springs is, , (a) Zero (by 43, , (ce) 12] (d) 1-25. (C.P.M.T.), If a force F applied on a body moves it with a, yelocity % then power will be, , (a) Frit (b) Pat, , (c) Ft (d) Fa (C.P.M.T.), , 40. An object of mass 40 kg and having velocity 4, m/s collides with another object of mass 60 ky, having velocity 2 m/s. ‘The loss of energy when, the collision is perfectly inelastic ts, , (a) 392] (6) 440), (c) 48) (d) 1101., (C.P.M.T.), 41, Inwhich case does the potential energy decrease ?, (a) on compressing the spring, (b) on stretching a spring, , (c) an moving a boxy against gravitational pull, (d) on the raising of an air bubble in water, (P.M.T. MP.), , 42. A4kgmassandal kg mass are moving with equal, Kinetic energies. The ratio of their momenta is, , (a)1:2 (6)1:1, (¢)2:1 (d)4:1., (Pre-Medical Dental, 1997), 43. Which of the following is not conserved in inelastic collision, (2) Momentum, (b) Kinetic energy, , (c) Both momentum and kinetic energy, (d) Neither momentum nor kinetic energy., (C.E.T. Chandigarh 1997), , 44. The first ball of mass m moving with the velocity, » collides head on with the second ball of mass m, at rest. If the coefficient of restitution is ¢, then, the ratlo of the velocities of the first and the, second ball after the collision is, , @ tse sts, @+5* w5*, , (MEE. BHU. 1997), , 45. Particle A makes a perfectly elastic cellision with ", another particle B at rest. They fly apart in op- £, posite direction with equal speeds. The ratio of it, , my, their masses — is, my, , (@} 5