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Subjects · Leaving Cert Physics

Leaving Cert Physics: Momentum

How often Momentum comes up on the Physics papers, every year it was asked, and questions to try.

HL Asked on 7 of the last 10 Higher Level papers, most recently in 2026. most years

OL Asked on 8 of the last 10 Ordinary Level papers, most recently in 2025. most years

June 2027 is the first exam on the new Physics course. These come from the 2016–2026 papers, so read them as a guide.

Momentum, Higher Level(8 marks)

Quick ones on Momentum.

(a)SI unit of momentum?
  1. kg m s⁻²
  2. kg m s⁻¹
  3. N m
(b)Momentum of a 1500 kg car travelling at 20 m s⁻¹?
  1. 30 000 N
  2. 75 kg m s⁻¹
  3. 30 000 kg m s⁻¹
(c)A 2.0 kg trolley moving at 3.0 m s⁻¹ hits and sticks to a stationary 4.0 kg trolley. Common velocity?
  1. 1.0 m s⁻¹
  2. 3.0 m s⁻¹
  3. 1.5 m s⁻¹
Show the answers

(a) kg m s⁻¹

(b) 30 000 kg m s⁻¹

(c) 1.0 m s⁻¹

Your turn: Higher Level questions on Momentum.

Higher Level

Asked on 7 of the last 10 Higher Level papers, most recently in 2026. most years

Every paper, year by year

YearWhere it came up
2026Q7
2025Q2
2024Not asked
2023Q7
2022Not asked
2021Q7
2019Not asked
2018Q1
2017Q5(b)
2016Q12(a)

Links open the State Examinations Commission’s paper for that year.

More Momentum questions

Momentum, 3 marks

State the principle of conservation of momentum.

  1. The total kinetic energy is always the same before and after a collision
  2. In a closed system the total force on the bodies is the same before and after a collision
  3. In a closed system the total momentum before a collision equals the total momentum after it
Show the answer

In a closed system the total momentum before a collision equals the total momentum after it

It follows from Newton's third law. Kinetic energy is only conserved as well if the collision is perfectly elastic.

Momentum, 2 marks

How is conservation of momentum applied to a collision in two dimensions?

  1. To the speeds of the bodies, ignoring their directions of motion
  2. Separately to the momentum components in two perpendicular directions
  3. Only in the direction in which the first body was moving
Show the answer

Separately to the momentum components in two perpendicular directions

Momentum is a vector. Resolve every velocity into x and y parts; total x-momentum is conserved and total y-momentum is conserved.

Ordinary Level

Asked on 8 of the last 10 Ordinary Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2026Not asked
2025Q1
2024Q6(a), Q7
2023Q14(a)
2022Not asked
2021Q7
2019Q5(a)
2018Q6
2017Q6
2016Q1, Q12(a)

Links open the State Examinations Commission’s paper for that year.

More Momentum questions

Momentum, 3 marks

Momentum of a 0.5 kg ball moving at 12 m s⁻¹?

  1. 24 kg m s⁻¹
  2. 36 kg m s⁻¹
  3. 6 kg m s⁻¹
Show the answer

6 kg m s⁻¹

p = mv = 0.5 × 12 = 6 kg m s⁻¹. 24 comes from dividing by 0.5; 36 is the kinetic energy in joules.

Momentum, 2 marks

A rifle recoils (kicks back) when fired. Which principle explains this?

  1. The law of flotation
  2. Conservation of momentum
  3. Conservation of mass
Show the answer

Conservation of momentum

Total momentum is zero before firing, so after firing the bullet's forward momentum is balanced by the rifle's backward momentum.

Momentum, 3 marks

Two skaters at rest push each other apart. Their total momentum afterwards?

  1. Zero
  2. Equal to their total mass
  3. Greater than zero
Show the answer

Zero

Momentum was zero before, so it is zero after. The skaters move off in opposite directions with equal and opposite momentum.

Other Physics topics

All of Leaving Cert Physics