Grade 12 Physical Sciences · Mechanics

State momentum laws and definitions

State momentum definitions and laws in full, for example momentum, impulse, an isolated system or conservation of linear momentum.

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Principle of Conservation of linear momentum Grade 12Miss Martins Maths and Science

Grade 12 momentum Newtons second law in terms of momentumMiss Martins Maths and Science

3)Newton 2nd law momentum | IntroKevinmathscience

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Question 4.1 · November 2025 · Paper 1 · National (DBE) · 2 marks

Cricketers at an academy conduct an experiment to determine the relationship between the contact time and the final momentum of a ball for a constant average net force.

A cricket ball of mass

150

g is thrown horizontally with a certain initial velocity and is struck by a bat so that the ball moves in the opposite direction, as shown in the diagram below. The average net force acting on the ball is horizontal.

The experiment is repeated using the same ball. The average net force and the initial velocity of the ball are kept constant. The contact time between the bat and the ball is changed EACH time. The results obtained are shown in the sketch graph below. Diagram for this question

4.1 Define the term impulse.(2)

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More past paper questions: state momentum laws and definitions

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3. Question 4.1 · May/June 2024 · Paper 1 · National (DBE) · 2 marks
Two trolleys A and B of mass $3, 2$ kg and $2, 6$ kg respectively are held at rest on a straight horizontal, frictionless track, with a compressed spring between them, as shown in the diagram below.

After the trolleys are released, the spring extends to its natural length and then falls onto the track. Trolley A now moves with a constant velocity of $0, 4$ m·s $^{- 1}$ to the left, while trolley B moves with a constant unknown velocity to the right. Trolley B reaches the end of the track after $1, 3$ s.
4.1 State the principle of conservation of linear momentum in words.(2)
Show the memo (1 tick)Memo
1. ✓
  Principle of conservation of linear momentumIn an isolated system the total (linear) momentum is conserved/remains constant.
  2 marks · State momentum laws and definitions
4. Question 4.1 · May/June 2023 · Paper 1 · National (DBE) · 2 marks
Trolley A of mass $7, 2$ kg moves to the right at $0, 4$ m·s $^{- 1}$ in a straight line on a horizontal floor. It collides with a stationary trolley B of mass $5, 3$ kg.

After the collision, the trolleys lock together and move to the right, as shown in the diagram below.

Ignore any frictional effects.
4.1 State the principle of conservation of linear momentum in words.(2)
Show the memo (1 tick)Memo
1. ✓
  Principle of conservation of linear momentumIn an isolated system the total (linear) momentum is conserved/remains constant.
  2 marks · State momentum laws and definitions
5. Question 4.3 · November 2023 · Paper 1 · National (DBE) · 2 marks
A wooden trolley of mass $2, 7$ kg moves to the left with a constant velocity of $3$ m·s $^{- 1}$ . A bullet of mass $0, 03$ kg is fired horizontally from the left towards the trolley. (See DIAGRAM 1.)

The bullet strikes the trolley and comes to rest inside the trolley in $0, 02$ s. The average net force exerted by the trolley on the bullet during this time is $591$ N. The bullet-trolley combination now moves to the right. (See DIAGRAM 2.)

Ignore all frictional and rotational effects.
4.3 State the principle of conservation of linear momentum in words.(2)
Show the memo (1 tick)Memo
1. ✓
  Principle of conservation of linear momentumThe total (linear) momentum in an isolated system is conserved/remains constant.
  2 marks · State momentum laws and definitions
6. Question 4.1 · May/June 2022 · Paper 1 · National (DBE) · 2 marks
4.1 What is meant by an isolated system in physics?(2)
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  Definition of an isolated systemA system on which the resultant/net external force is zero.
  2 marks · State momentum laws and definitions

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