IB Physics HL A.2.20 Collisions and Conservation of Energy

Practise analysing HL collisions with energy loss, combined masses, pellets and complex momentum evidence.

Exam points

distinguish elastic collisions, inelastic collisions and explosions using momentum and kinetic-energy outcomes
apply conservation of momentum to two-body collisions or explosions with signed velocities
compare kinetic-energy changes to decide whether a collision is elastic, inelastic or an explosion

[Maximum number: 2]

This question is in two parts. Part 1 is about momentum and energy. Part 2 is about the de Broglie hypothesis and radioactive decay.

Jane and Joe are two ice skaters initially at rest on a horizontal skating rink. They are facing each other and Jane is holding a ball. Jane throws the ball to Joe who catches it. The speed at which the ball leaves Jane, measured relative to the ground, is $8.0 \mathrm{~ms}^{-1}$ . The following data are available.

\begin{aligned} & \text { Mass of Jane }=52 \mathrm{~kg} \\ & \text { Mass of Joe }=74 \mathrm{~kg} \\ & \text { Mass of ball }=1.3 \mathrm{~kg} \end{aligned}

Use the data to calculate the

speed V of Joe relative to the ground immediately after he catches the ball.

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A.2.20—Elastic and inelastic collisions question 1