A raindrop is falling through the air with an increasing velocity - Edexcel - A-Level Physics - Question 5 - 2023 - Paper 2

To analyze the forces acting on the raindrop, we consider the forces involved:

• The weight $W$ acts downwards due to gravity.
• The upthrust $U$ acts upwards, counteracting some of the weight.
• The viscous drag $F$ also acts upwards, opposing the motion of the raindrop.

As the raindrop accelerates downwards, its weight $W$ is greater than the sum of the upthrust $U$ and the drag force $F$. Therefore, we express this relationship as: $W > U + F$ Rearranging gives: $F + U < W$ This is consistent with the choice D, which correctly indicates that the total upward forces ($F + U$) are less than the downward force (weight $W$).