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Free Collisions MCQs with Answers

22 Collisions MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Collisions involve the conservation of linear momentum when bodies interact for a short time. The topic covers impulse, elastic and inelastic collisions, kinetic energy changes, and the coefficient of restitution, with calculations usually based on one dimensional motion. Momentum remains conserved in isolated collisions, but kinetic energy is conserved only in elastic collisions.

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22 questions · page 1 of 2

1. A body of mass 2 kg moving at 3 m s-1 collides and sticks to a stationary body of mass 4 kg. The common velocity after impact is

  • A. 0.5 m s-1
  • B. 1 m s-1
  • C. 1.5 m s-1
  • D. 2 m s-1

Explanation: Momentum is conserved, so the initial momentum of 2 times 3, which is 6 kg m s-1, is shared by the combined mass of 6 kg, giving a…

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Correct answer: 1 m s-1

2. In an elastic collision, which quantity is conserved in addition to momentum?

Easy
  • A. Kinetic energy
  • B. Mass alone
  • C. Velocity of each body
  • D. Potential energy

Explanation: An elastic collision is defined by the conservation of kinetic energy as well as momentum, and collisions between gas molecules are…

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Correct answer: Kinetic energy

3. In an isolated system, the total linear momentum

Very hard
  • A. always increases
  • B. is conserved, whatever type of collision occurs
  • C. is conserved only in elastic collisions
  • D. is zero

Explanation: Momentum conservation follows from Newton's third law and holds in every collision and explosion provided no external force acts, whether…

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Correct answer: is conserved, whatever type of collision occurs

4. In a perfectly inelastic collision, the two bodies

  • A. bounce apart with no loss of kinetic energy
  • B. stick together and move with a common velocity, losing some kinetic energy
  • C. conserve kinetic energy but not momentum
  • D. come to rest

Explanation: Momentum is still conserved, so the common velocity follows from the total momentum divided by the total mass, but some kinetic energy is…

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Correct answer: stick together and move with a common velocity, losing some kinetic energy

5. A body of mass 2 kg moving at 3 m per second collides and sticks to a stationary body of mass 4 kg. Their common velocity is

  • A. 1 m per second
  • B. 1.5 m per second
  • C. 0.5 m per second
  • D. 3 m per second

Explanation: Total momentum before is 2 multiplied by 3, that is 6 kg m per second, and the combined mass afterwards is 6 kg, so the common velocity is…

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Correct answer: 1 m per second

6. In an elastic collision between two bodies of equal mass, one moving and one at rest

  • A. they stick together
  • B. the moving body stops and the stationary one moves off with the original velocity
  • C. both move off at half the original velocity
  • D. the moving body rebounds

Explanation: Conserving both momentum and kinetic energy for equal masses gives a complete exchange of velocities, which is what makes the Newton's…

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Correct answer: the moving body stops and the stationary one moves off with the original velocity

7. If a body having mass m1 (2 kg) moving with 5 m/s approaches another mass m2 (3 kg) with speed of 1 m/s in same direction, relative speed of approach is 4 m/s. Relative speed of separation after collision will be:

  • A. 4 m/s
  • B. 2 m/s
  • C. 6 m/s
  • D. Depends on masses

Explanation: For a perfectly elastic collision the relative speed of separation equals the relative speed of approach, whatever the masses, which…

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Correct answer: 4 m/s

8. When collision between the bodies in a system is inelastic in nature then for system ____________________?

  • A. momentum changes but K.E remain conserve
  • B. K.E changes but momentum remain conserve
  • C. both momentum and K.E changes
  • D. both momentum and K.E remain conserve

Explanation: In an isolated system, internal forces during an inelastic collision cancel in pairs, so total momentum remains conserved, while some…

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Correct answer: K.E changes but momentum remain conserve

9. A body is hanging from a rigid support by an extensible string of length L. It is struck inelastically by an identical body of mass m with horizontal velocity v =√2gl , the tension in the string increases just after striking by:

  • A. mg
  • B. 3mg
  • C. 2mg
  • D. None of these

Explanation: Initially, the tension in the string is T = mg, which equals the weight of the hanging body.

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Correct answer: 2mg

10. Two equal masses travel towards each other on a frictionless air track at speeds of 60 cms-1 and 30cms-1. They stick together on impact.What is the speed of the masses after impact?

  • A. 15 cm s-1
  • B. 30 cm s-1
  • C. 20 cm s-1
  • D. 45 cm s-1

Explanation: The principle of conservation of momentum states that the total momentum before an impact is equal to the total momentum after the impact.

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Correct answer: 15 cm s-1

11. A ball moving horizontally with speed 'v' strikes the bob of a simple pondulum at rest The mass of the bob is equal to that of the ball If the collision is elastic the bob will to a height:

  • A. V g
  • B. V/2g
  • C. V/4g
  • D. V²/8g E. V²/7g

Explanation: The explanation for this question will be added soon.

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Correct answer: V²/8g E. V²/7g

12. In perfect elastic collision

  • A. Only momentum is conserved
  • B. Only total energy is conserved
  • C. Only kinetic energy is conserved
  • D. Momentum, kinetic energy, and total energy is conserved

Explanation: Kinetic energy and hence momentum is conserved only in elastic collision.

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Correct answer: Momentum, kinetic energy, and total energy is conserved

13. An elastic collision is the one In which:

  • A. Kinetic energy and momentum is conserved
  • B. Kinetic energy is conserved but total energy is not conserved
  • C. Momentum is conserved but kinetic energy is not conserved
  • D. Both kinetic energy and momentum are not conserved

Explanation: An elastic collision is a collision in which there is no net loss in kinetic energy in the system as a result of the collision.

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Correct answer: Kinetic energy and momentum is conserved

14. In a perfectly elastic collision:

  • A. Only momentum is conserved
  • B. Only total energy is conserved
  • C. Only kinetic energy is conserved
  • D. Momentum, kinetic energy, and total energy are all conserved.

Explanation: In such collisions, not only is momentum conserved, but the kinetic energy and total energy of the system also remain constant before and…

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Correct answer: Momentum, kinetic energy, and total energy are all conserved.

15. A particle of mass 'm' is projected from the ground with an initial speed uo at an angle 'a' with the horizontal. At the highest point of its trajectory, it makes a completely in inelastic collision with another particle of mass which was thrown vertically upward from the ground with the same initial speed uo. The angle that the composite system makes with the horizontal immediately after the collision is?

  • A. 45°
  • B. 45°-a
  • C. 45°+a
  • D. 90°

Explanation: Tan θ = momentum of first collision/ momentum of second collision= 1 Tan 1 = 45°

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Correct answer: 45°

16. A particle of mass 'm' is projected from the ground with an initial speed u0 at an angle 'α' with the horizontal. At the highest point of its trajectory, it makes a completely in-elastic collision with another particle of mass 'm' which was thrown vertically upward from the ground with the same initial speed u0. The angle that the composite system makes with the horizontal immediately after the collision is?

  • A. 45°
  • B. 45°-α
  • C. 45°+α
  • D. 90°

Explanation: : It is numerical and it can have only one possible answer.

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Correct answer: 45°

17. A particle of mass 'm' is projected from the ground with an initial speed u0 at an angle 'a' with the horizontal. At the highest point of its trajectory, it makes a completely inelastic collision with another particle of mass which was thrown vertically upward from the ground with the same initial speed u0. The angle that the composite system makes with the horizontal immediately after the collision is _.

  • A. 37˚
  • B. 45˚-a
  • C. 45˚+a
  • D. 90˚

Explanation: Option A is correct since by applying the formula shown in the picture of v1 and v2.

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Correct answer: 37˚

18. In elastic collision, when a massive body collides with light body at conditions m1 >> m2 and v2 = 0 ms-1, then the change in velocity will be written as:

  • A. v1' ≈ −v1 ; v2' ≈ v1
  • B. v1' ≈ v1 ; v2' ≈ 0
  • C. v1' ≈ v1 ; v2' ≈ 2v1
  • D. v1' ≈ −v1 ; v2' ≈ 0

Explanation: Explanation:V1' = (m1 - 0/m1 + 0) v1 + (2(m2) (0)/0 +m2) V1' = (m1 / m2) v1 + 0V1' = v1 + 0V1' = v1V2' = (2m1v1 / m1) + (0 - m1 / m1 + 0)…

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Correct answer: v1' ≈ v1 ; v2' ≈ 2v1

19. A particle of mass moving with velocity V makes head. One elastic collision with another particle of the same mass and initially at rest. The velocity of the first particle after the collision:

  • A. 2V
  • B. -V
  • C. +V
  • D. Zero

Explanation: -V: This option is correct. In an elastic collision, the first particle will experience a change in direction and will have a velocity…

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Correct answer: -V

20. A object of mass "m" travelling with speed "v" has a head-on collision with another object of mass "m" travelling with speed "v" in the opposite direction, the object sticks together after the collision.What is the total loss of kinetic energy in the collision?

  • A. 0
  • B. 1/2mv2
  • C. mv2
  • D. 2mv2

Explanation: Since there are two equal masses travelling with the equal velocity. Therefore according to the law of conservation of kinetic…

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Correct answer: mv2
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Collisions MCQs: common questions

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