A Level Physics Practice Exam

What is the speed vs. time graph for a parachutist during a jump expected to show initially?

1. A constant speed

2. A decreasing speed

3. An increasing speed

4. A rapid drop to terminal velocity

The correct answer is: A rapid drop to terminal velocity

In the context of a parachutist's jump, initially, the speed versus time graph is expected to show a rapid increase in speed as the parachutist accelerates due to gravity. Initially, when the parachutist jumps from the plane, they experience a free fall, which means gravity is the dominant force acting on them, resulting in an increase in speed. As they continue to fall, the drag force from the air becomes significant. Initially, the drag force is not sufficient to counteract the gravitational force, so the parachutist continues to accelerate downward. As the speed increases, the drag force increases as well, eventually leading to a point where the two forces balance each other out—this is known as terminal velocity. The rapid increase in speed will continue until this balance is reached, resulting in a graph that shows a steep increase in speed at first. This behavior is characteristic of free fall until terminal velocity is approached, reflecting the rapid drop to terminal velocity in the initial phase of the jump. The parachutist will not maintain constant speed or decrease speed at the very beginning of the jump.