Questions on Pressure

Q11. A pen cap floats in a plastic lemonade bottle three-quarters full of water .

If you squeeze the bottle the pen cap sinks to the bottom. If you then let go of the bottle, the pen cap floats to the surface

(a) When the bottle is squeezed what, if anything, happens to:

(i) the distance between the air molecules inside the bottle?

(1 mark)

(ii) the distance between the water molecules inside the bottle?

(1 mark)

(iii) the pressure of the air trapped inside the pen cap?

(1 mark)

(iv) the volume of the air trapped inside the pen cap?

(1 mark)

(b) Explain why the pen cap sinks when you squeeze the bottle.

(2 marks)

Maximum 6 marks