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Physics Form 4 Chapter 2 Force and Motion I
Collision 2. Types of collision

1. The principle of conservation of momentum There are two types of collision, that is, elastic
can be studied using the collision of objects. collision and inelastic collision.
(a) In an elastic collision
(i) momentum is conserved,
2.0 kg 1.0 kg At rest
3.0 m s –1 v m s –1
A B A B (ii) kinetic energy is conserved,
(iii) the objects move separately after
(a) collision ,
(iv) total energy is conserved.
2.0 kg 3.0 m s –1 1.0 kg 2.0 m s –1 v m s –1 (b) In an inelastic collision.
A B A B
(i) momentum is conserved,
(b) (ii) kinetic energy is not conserved,
Figure 2.57 (iii) the objects may combine and move
For case (a) together after collision,
Chapter
2 Total momentum Total momentum (iv) total energy is conserved.
=
before collision after collision
(2.0 × 3.0) + (1.0 × 0) = (2.0 + 1.0)v SPM Tips
6.0 kg m s = 3.0 v
–1
Therefore, v = 2.0 m s –1 In the explanation of a law or principle, the conditions
and limitations must be mentioned together. In the case
For case (b) of stating the principle of conservation of momentum,
(2.0 × 3.0) + (1.0 × (–2.0)) = (2.0 + 1.0)v the condition of no external force acting on the system
needs to be mentioned.
4.0 kg m s = 3.0 v
–1
4.0
Therefore, v = 3.0
= 1.3 m s –1

Experiment 2.2
Eksperimen 2.1
Eksperimen 2.1
Problem statement: Is the total momentum constant in a closed system?

Aim: To show the total momentum in a closed system is constant for the case of collision.
Hypothesis: The total momentum before collision is the same as that of after collision if there is no
external force acting on the system.
Variables:
• Manipulated variable : Total momentum before collision
• Responding variable : Total momentum after collision
• Fixed variable : Friction compensated inclined plane

Apparatus and materials: Ticker timer, 12 V a.c. power supply, triple beam balance, 4 trolleys, inclined
plane, ticker tape, cellophane tape, and plasticine.

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