IB Physics HL A.2.16 Linear momentum conservation and recoil Question Bank

Practise IB Physics HL A.2.16 by analysing momentum conservation in collisions, recoil and multi-body systems.

Exam points

Apply vector momentum conservation to collisions, recoil or decay products.
Analyse a multi-stage momentum problem and match boundary velocities across stages.
Evaluate the isolated-system assumption and distinguish momentum conservation from kinetic-energy conservation.

[Maximum number: 2]

A girl on a sledge is moving down a snow slope at a uniform speed.

Figure for Question A.2.16—Linear momentum conservation question 1 — IB Physics HL

When the sledge is moving on the horizontal region of the snow, the girl jumps off the sledge. The girl has no horizontal velocity after the jump. The velocity of the sledge immediately after the girl jumps off is $4.2 \mathrm{~m} \mathrm{~s}^{-1}$ . The mass of the girl is 55 kg and the mass of the sledge is 5.5 kg . Calculate the speed of the sledge immediately before the girl jumps from it.

mention of conservation of momentum

OR
$5.5 \times 4.2=(55+5.5) \ll /><$

0.38 « $\mathrm{m} \mathrm{s}^{-1}$ »

Marking guidance:

Allow $p=p^{\prime}$ or other algebraically equivalent statement

Award [0] for answers based on energy

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A.2.16—Linear momentum conservation question 1