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CAIE A-Level Physics 3.3.3 Elastic Collision Conditions

Practise testing elastic collisions through momentum, kinetic energy and relative approach/separation speed.

Syllabus
2028–2030
Course
Physics 9702
Level
AS

3.3.3—That, for an elastic collision, total kinetic energy is conserved and the question 1

[Maximum number: 3]

Question (a)

(a)

Two blocks travel directly towards each other along a horizontal, frictionless surface. The blocks collide, as illustrated in Fig. 3.1.

Fig. 3.1

Fig. 3.1

Block A has mass 3 M and block B has mass M.
Before the collision, block A moves to the right with speed 0.40 ms−10.40 \mathrm{~ms}^{-1} and block B moves to the left with speed 0.25 ms−10.25 \mathrm{~ms}^{-1}.
After the collision, block A moves to the right with speed 0.20 m s−10.20 \mathrm{~m} \mathrm{~s}^{-1} and block B moves to the right with speed v.

[ 3 ]

Question (i)

(i)

Calculate, for the blocks,
1. the relative speed of approach,
relative speed of approach = ms−1\mathrm{m s}^{-1}
2. the relative speed of separation.
relative speed of separation = ms−1\mathrm{m s}^{-1}

[ 2 ]

Question (ii)

(ii)

Use your answers in (b)(iii) to state and explain whether the collision is elastic or inelastic.

[ 1 ]
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