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Class-10th, , Work power and Energy, , Full Chapter Numericals, Er. Sunny Kashyap
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Work,EnergyandPower, , , , Question 1., , Whenaforceof50Nactsonabody,thebodyisdisplacedthroughadistanceof3minadirectionnormalto the direction of the, force. The work done by the force, , (a) 150 J, , (b) 1470 J, , (c)Zero, , (d) -150, , vw JAnswer, , Answer:(c)Zero, , , , Question 2., , A body of mass 20 kg is initially at a height of 3 m above the ground. It is lifted to a height of 2 mfrom that, position. Its increase in potential energy is, , (a) 1004, , (b) 392J, , (c) 60J, , (d) -100, , w JAnswer, , Answer: (b) 392 J, , , , Question 3., , A wooden cube having mass 10 kg is dropped from the top of a building . After 1 s, a bullet ofmass 20 g fired at, it from the ground hits the block with a velocity of 1000 m/s at an angle of 30°tothehorizontalmoving, upwardsandgets imbeddedinthe block. The velocityofthe block/bulletsystem immediately after the collision is, (a) 17 m/s, , (b) 27 m/s, , (c) 52m/s, , (d) 10, , wv m/sAnsw, er, , Answer: (a) 17 m/s, , , , Question 4., , Abodyofmass1 Okgismovedparalleltotheground,throughadistanceof2m. Theworkdoneagainstgravitational force is, (a) 196 J, , (b) -196 J, , (c) 20, , (d) zeroA, , v nswer, , Answer:(d)zero, , , , Question 5., Aquantity of work of 1000 J is donein 2 seconds. The power utilised is, (a) 998 W, , v7) Edit with WPS Office
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(b) 1002 W, (c) 2000 W, (d) 500, , w WAnswe, r, , Answer: (d) 500 W, , , , Question 6., , Abodyofmass 1kgtravels withavelocity of10m/s, thisawall andrebounds.If 50%ofits initialenergyis wasted as heat,, its kinetic energy at the instant of rebounding is, , (a) 20J, , (b) 60J, , (c) 50J, , (d) 25, , w JAnswe, r, , Answer: (d) 25 J, , , , Question 7., , A marble moving with some velocity collides perfectly elastically head-on with another marble atrest having, mass 1.5 times the mass of the colliding marble. The percentage of kinetic energy bythe colliding marble after, the collision is, , (a) 4, , (b) 25, , (c) 44, , (d) 67, , wv AnswerAnsw, , er:(a)4, , , , Question 8., , Aparticleofmassmismovinginahorizontalcircleofradiusrunderacentripetalforcegivenby(-kr?) where k is a, constant , then, , (a) the total energy of the particle is (- k/2r), , (b) the kinetic energy of the particle is (k/r), , (c) the potential energy of the particle is (k/2r), , (d) the kinetic energy of the particle is (, vw k/r)Answer, , Answer: (a) the total energy of the particle is (- k/2r), , , , Question 9., , A sphere of mass m moving with a constant velocity u hits another stationary sphere of the samemass. If e is, the coefficient of restitution, then the ratio of velocity of the two spheres after thecollision will be, (a)l1-e/1te, , (b)1+e/1-e, , (c)e+1/e-1, , (d)e-1/er+, , wv 1Answer, , Answer: (a) 1-e/1+e, , v7) Edit with WPS Office
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Question 10., , Twomasses1 gand4garemovingwithequalkineticenergles. Theratioofthemagnitudesoftheir linear momenta is, (a) 4:1, , (b) 0:1, , (c)1:2, , (d) 1:, , w 6Answe, r, , Answer: (c) 1:2, , , , Question 11., , A ball is dropped from a height of 1 m. If the coefficient of restitution between the surface and ballis 0.6, the ball, rebounds to a height of, , (a) 0.6m, , (b) 0.4m, , (c) 1m, , (d) 0.36, , w mAnswer, , Answer: (d) 0.36 m, , , , Question 12., , A wooden cube having mass 10 kg is dropped from the top of a building. After 1 s, a bullet ofmass 20 g fired at, it from the ground hits the block with a velocity of 1000 m/s at an angle of 30°to the horizontal moving upwards, and gets imbedded in the block. The velocity of the block/bulletsystem immediately after the collision is, , (a) 17 m/s, , (b) 27 m/s, , (c) 52 m/s, , (d) 10, , v m/sAnsw, er, , Answer: (a) 17 m/s, , , , Question 13., , Abulletfiredintoafixedtargetloseshalfofitsvelocityafterpenetrating3cm.Howmuchfurtherwillit penetrate before, coming torest assuming that it faces constantresistance to motion?, , (a) 2.0cm, , (b) 3.0cm, , (c) 1.0cm, , (d) 1.5, , w cmAnsw, er, , Answer: (c) 1.0 cm, , , , Question 14., Abodyofmass5kgisinitially ataheightof1 Omabove theground.Itisthenmovedto anotherplace40 m from this position, inthe same horizontal level. Its increasein potential energy is, , (a) 200 J, (b) 1960 J, v7) Edit with WPS Office
