A vertical tube is filled with a liquid. As shown in Fig. 2.1, a metal ball is kept stationary by a thread just under the liquid surface. The tube’s diameter is much larger than the ball’s diameter. When the ball is let go, it moves downwards with uniform acceleration for a short time. Fig. 2.1 (not to scale) shows: thread, metal ball, tube and liquid.
(a)[2]
Describe the change in the ball’s velocity during the short interval while it accelerates downwards uniformly.
(b)[3]
The ball reaches terminal velocity. Describe and explain the motion of the ball from release until terminal velocity is reached.
(c(i))[2]
Calculate the gravitational potential energy transferred from the ball during its fall.
(c(ii))[3]
Calculate the kinetic energy of the ball at the bottom of the tube.
(c(iii))[1]
Explain why the result in (c)(i) is not the same as the result in (c)(ii).
Worked solution & mark scheme
This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Velocity/speed rises with time” …