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Leaving Cert Physics & Chemistry: Newton's laws & momentum

How often Newton's laws & momentum comes up on the Physics & Chemistry papers, every year it was asked, and questions to try.

HL Asked on 9 of the last 9 Higher Level papers, most recently in 2025. banker

OL Asked on 9 of the last 9 Ordinary Level papers, most recently in 2025. banker

Newton's laws & momentum, Higher Level(7 marks)

Quick ones on Newton's laws & momentum.

(a)Newton's first law: a body stays at rest or moves with constant velocity unless…
  1. Its mass changes while it is moving along
  2. An unbalanced external force acts on it
  3. It is placed on a frictionless surface
(b)A net force of 30 N acts on a 6 kg mass. Its acceleration?
  1. 0.2 m s⁻²
  2. 180 m s⁻²
  3. 5 m s⁻²
(c)Newton's second law: the rate of change of momentum of a body is proportional to…
  1. The resultant force, and in its direction
  2. Its velocity, and in the opposite direction
  3. Its mass only, and in the direction of motion
Show the answers

(a) An unbalanced external force acts on it

(b) 5 m s⁻²

(c) The resultant force, and in its direction

Your turn: Higher Level questions on Newton's laws & momentum.

Higher Level

Asked on 9 of the last 9 Higher Level papers, most recently in 2025. banker

Every paper, year by year

YearWhere it came up
2025Q1(a), Q1(c), Q2
2024Q2
2023Q1(a), Q1(c), Q1(d)
2022Q1(b), Q1(c), Q2, Q6(a)
2021Q1(c), Q2
2019Q1(a), Q1(d)
2018Q1(b), Q2
2017Q1(a), Q2
2016Q1(b), Q1(c), Q2

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

More Newton's laws & momentum questions

Newton's laws & momentum, 3 marks

Why do standing passengers lurch forward when a bus brakes suddenly?

  1. The bus pushes them forwards
  2. The braking increases their weight
  3. Their bodies tend to keep moving forward
Show the answer

Their bodies tend to keep moving forward

Newton's first law (inertia): a body keeps its velocity unless a force acts. The bus slows but no force has yet acted to slow the passengers, so they carry on forward.

Newton's laws & momentum, 2 marks

Total momentum is conserved in a collision provided that…

  1. No kinetic energy is lost in the collision
  2. No external force acts on the system
  3. The objects stick together afterwards
Show the answer

No external force acts on the system

Momentum is conserved in every collision, sticky or bouncy, elastic or not, as long as no outside force (such as friction) acts on the colliding bodies.

Newton's laws & momentum, 3 marks

2 kg at 5 m s⁻¹ hits 3 kg moving towards it at 2 m s⁻¹. They stick together. Common velocity?

  1. 0.8 m s⁻¹
  2. 3.2 m s⁻¹
  3. 2 m s⁻¹
Show the answer

0.8 m s⁻¹

Take the 2 kg direction as positive: 2(5) + 3(−2) = 4 kg m s⁻¹. v = 4/5 = 0.8 m s⁻¹. Adding the momenta (16/5) ignores direction.

Ordinary Level

Asked on 9 of the last 9 Ordinary Level papers, most recently in 2025. banker

Every paper, year by year

YearWhere it came up
2025Q1(a), Q1(d), Q6(a)
2024Q1(c), Q6(a)
2023Q1(d), Q2, Q6(a)
2022Q1(c), Q2, Q6(a)
2021Q1(b), Q6(a)
2019Q1(a), Q6(a)
2018Q1(b), Q6(a)
2017Q1(a), Q6(a)
2016Q1(c), Q1(d), Q2

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

More Newton's laws & momentum questions

Newton's laws & momentum, 2 marks

Newton's first law: a body stays at rest or at constant velocity unless?

  1. Its mass changes as it moves
  2. Friction on it becomes zero
  3. An external force acts on it
Show the answer

An external force acts on it

With no overall force, nothing changes: a still object stays still and a moving one keeps the same speed and direction. This tendency is called inertia.

Newton's laws & momentum, 2 marks

Momentum is defined as?

  1. Force × distance
  2. Mass × velocity
  3. Mass × acceleration
Show the answer

Mass × velocity

p = mv, unit kg m/s. Mass × acceleration is force; force × distance is work.

Newton's laws & momentum, 2 marks

Newton's second law: the rate of change of momentum is proportional to?

  1. The applied force
  2. The mass only
  3. The distance travelled
Show the answer

The applied force

The full law also says the change is in the direction of the force. It leads to F = ma, which gives the newton its definition.

Other Physics & Chemistry topics

All of Leaving Cert Physics & Chemistry