The diagram in the figure shows a device which makes use of the principle of transmission of
pressure.

(i) Name the parts labelled by the letters X and Y.
(ii) Describe what happens to the valves A and B and to the
quantity of water in the two cylinders when the lever arm is moved down.
(iii) Give reasons for what happens to the valves A and B in
part (ii).
(iv) What happens when the release valve is opened?
(v) What happens to the valve B in cylinder P when the lever
arm is moved up?
(vi) Give a reason for your answer in part (v)
(vii) State one use of the above device.