Physics (AS & A Level) · Oct / Nov 2022 · Paper 11 · Question 15

A box, in the shape of a cube, falls from a ship into the sea. The box lands with its lower face level with the surface of the sea. The box begins to sink, becomes totally submerged and then sinks deeper into the sea. As the box sinks, its lower face is always parallel to the surface of the sea. Which graph best represents the variation of the upthrust acting on the box with the depth of its lower face below the surface of the sea?

1. AGraph A: upthrust increases linearly from origin with depth
2. BGraph B: upthrust constant from origin with depth
3. CGraph C: upthrust increases linearly then becomes constant
4. DGraph D: upthrust increases with decreasing gradient then becomes constant

As printed in the paper