Momentum

Question 1

What is momentum?

Answer 1

Momentum is the product of mass and velocity:
Momentum = m × v.

Question 2

What is impulse, and how is it calculated?

Answer 2

Impulse is the product of force and the change in time:
Impulse = F Δt = Δ(m v).

Question 3

How is force related to the rate of change of momentum?

Answer 3

Force is the rate of change of momentum:
F = Δ(m v) / Δt.

Question 4

Give examples of safety features that reduce force during collisions.

Answer 4

• Seat belts
• Airbags
• Crumple zones
• Bending knees while jumping

These increase Δt, reducing F, and lowering harm.

Question 5

State the law of conservation of momentum.

Answer 5

In a closed system, the total momentum before a collision equals the total momentum after the collision:
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂.

Question 6

Differentiate between elastic and inelastic collisions.

Answer 6

• Elastic Collision: Momentum and kinetic energy are conserved.
• Inelastic Collision: Momentum is conserved, but kinetic energy is not.

Question 7

How does momentum change for a bullet and a lorry?

Answer 7

Momentum is conserved regardless of mass:
mₘ₁bullet vₘ₁bullet = Mₘ₁lorry vₘ₁lorry.

Question 8

How does increasing the time of impact reduce injury in collisions?

Answer 8

Increasing Δt reduces the force F = Δ(m v) / Δt, minimizing injury.

Question 9

What does it mean if two objects stick together after a collision?

Answer 9

It indicates an inelastic collision where the final velocities of both objects are the same:
V₁ = V₂ = V.

Question 10

What should you do to solve investigation questions in Paper 6?

Answer 10

1. Read the question carefully multiple times.
2. Look for the word ‘investigate’ to identify the problem.
3. Your investigation is the solution to the given question.