Physics (AS & A Level) · Oct / Nov 2022 · Paper 13 · Question 9

An air bubble in a tank of water is rising with terminal (constant) velocity. The forces acting on the bubble are X, Y and Z, as shown. The upthrust on the bubble is X. Which statement about the forces is correct?

1. AZ is the viscous force on the bubble, Y is the weight of the bubble and X = Y + Z.
2. BZ is the viscous force on the bubble, Y is the weight of the bubble and X > Y + Z.
3. CZ is the weight of the bubble, Y is the viscous force on the bubble and X = Y + Z.
4. DZ is the weight of the bubble, Y is the viscous force on the bubble and X > Y + Z.

As printed in the paper