Question

Label the forces acting on the box. (Please say where each force belongs)

Answer 1

Answer:

The box first accelerates with a negative (downward) acceleration until it hits the water. Upon hitting the water, the box experiences a balance of forces (50 N downwards due to gravity and 50 N upwards due to the water). Thus, the box will finish its motion moving with a constant velocity.

Identifying which forces are acting on an object is pretty straightforward. You need to have an understanding of the different types of forces and how they affect objects, such as gravity pulling objects down or friction acting against an object's motion. Then, if it helps, you can draw a free-body diagram.