1.17 describe the forces acting on falling objects and explain why falling objects reach a terminal velocity

You will normally get asked about 2 scenarios where terminal velocity acts on an object:

1. In air - the force acting upwards is air resistance
2. In liquid - the forces acting upwards are drag and upthrust

Otherwise they all follow the same pattern:

1. As the object is release, it begins to accelerate rapidly downwards due to gravitational pull.

2. As the speed increase, so does the opposing frictional force.

3. Eventually, the opposing force catches up and equals the downwards gravitational pull force. The object has now reached terminal velocity.

You will also see terminal velocity represented graphically.

The curve shows how the rate of acceleration is decreasing as the opposing force increases.

The straight line shows terminal velocity.

A very common question is the typical parachutist question, so here is a diagram for you.

The parachutist reaches terminal velocity at around 25 seconds, before opening his parachute, decelerating rapidly, and the finding a new terminal velocity.