Physics · Oct / Nov 2020 · Paper 41 · Question 2
0625
As printed in the paper
The question as text
A vertical tube contains a liquid. A metal ball is held at rest by a thread just below the surface of the liquid, as shown in Fig. 2.1. tube liquid thread metal ball Fig. 2.1 (not to scale) The diameter of the tube is much greater than the diameter of the ball. The ball is released and it accelerates downwards uniformly for a short period of time.
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2(a)[2]
it / velocity / speed changes / increases (with time)
it / velocity / speed increases at constant rate / steadily
2(b)[3]
any three from:
(initial) acceleration caused by weight / force of gravityacceleration decreasesdrag / resistance force increases (with speed)(finally / at terminal velocity) no acceleration / constant speed(finally / at terminal velocity) no resultant force2(c)(i)[2]
(GPE =) mg (∆) h (in any form) or 0.0021 × 10 × 0.80 or 2.1 × 10 × 0.80
or 17 (J)
0.017 J
2(c)(ii)[3]
(KE =) 1
2 mv 2 (in any form)
2 × 0.0021 × 1.22 or 1
1
2 × 2.1 × 1.22 or 1.5 (J)
1.5 × 10–3 J
2(c)(iii)[1]
(work done against) friction / drag / resistance or thermal energy generated or (displaced) liquid gains gravitational potential energy
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