IB Physics SL A.2.22 Kinetic Energy in Collisions

Practise comparing kinetic energy before and after collisions and explaining energy transfer into deformation and internal energy.

Exam points

Calculate kinetic-energy loss and classify collision outcomes.
Explain energy transfer from motion into deformation and internal energy.

[Maximum number: 3]

A horizontal rigid bar of length 2 R is pivoted at its centre. The bar is free to rotate in a horizontal plane about a vertical axis through the pivot. A point particle of mass M is attached to one end of the bar and a container is attached to the other end of the bar.

A point particle of mass $\frac{M}{3}$ moving with speed v at right angles to the rod collides with the container and gets stuck in the container. The system then starts to rotate about the vertical axis.

The mass of the rod and the container can be neglected.

Figure for Question A.2.22—Collision energy question 1 — IB Physics SL

Determine in terms of M and v the energy lost during the collision.

$\begin{aligned} \text { initial } K E=\frac{M v^{2}}{6} \text { final } K E=\frac{M v^{2}}{24} \end{aligned}$

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A.2.22—Collision energy question 1