JEE Physics - Work Energy and Power

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Question - 1

A metre -strick of mass 200 g stands vertical on the ground .Work done to the make it lie horizontal on the ground is

  • A zero
  • B 0.2J
  • C 1.96J
  • D 0.98J

Question - 2

A body of mass 2 kg moves linearly at the speed of 10 ms-1 .A force F is applied on it due to which it moves with a speed of 20 ms-1 ,after covering a distance 3m .The magnitude of F is

  • A 100 N
  • B 10N
  • C 33.3 N
  • D 19.6 N

Question - 3

A mettalicsphere and a football with a same kinetic enregy are brought to rest by the application of the same retarding force.Assume no friction between the surfaces

  • A The football will come to rest in a shorter time
  • B The sphere will come to rest in a shorter time
  • C Both will come to rest in a shorter time
  • D Sphere will cover shorter distance

Question - 4

Consider a one-dimensional elastic collision between an incomming body P of mass m1 and another body Q  of mass m2 initially at rest .for body Q to move with the greatest kinetic energy after the collision

  • A m1>m2
  • B m1<m2
  • C m1=m2
  • D the body P must recoil back

Question - 5

A body of mass 1 kg falls from a height 1 m on the ground and it strikes the ground after time t.The momentum of the body is

  • A 2g
  • B \(2\sqrt g\)
  • C \(\sqrt{2g}\)
  • D \(\sqrt g\)

Question - 6

A collision is said to be elastic if

  • A elastic bodies collide
  • B inelastic bodies collide
  • C total linear momentum is conserved
  • D total energy before and after the collision remains the same

Question - 7

A body of mass 8 kg at rest is situated at 20 m from the ground.If it is released till its kinetic energy becomes equal to potential energy ,its velocity at that instant would be

  • A 14 ms-1
  • B 9.8 ms-1
  • C 196 ms-1
  • D 392 ms-1

Question - 8

For a body falling freely ,the ratio between potential enegy (P) and kinetic energy (K) at a given instant is 5:1 .When the velocity of the body increases by 100% ,the ratio \(P\over K\) at that instant is

  • A 1:1
  • B 1:2
  • C 1:5
  • D 2:1

Question - 9

In an elastic collision

  • A velocity always remains constant
  • B linear momentum of each particle remains constant
  • C loss in kinetic enregy equals the amount of workdone
  • D total kinetic energy of the particles comprising the system remains constant

Question - 10

A road of length 8 m and mass of 10 kg lies on the ground horizontally .It is desired to make it stand vertical on the ground .The work done (in J) is

  • A 80
  • B 392
  • C 784
  • D 40
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