Question

A skydiver jumps out of a plane and begins to accelerate. His acceleration slows until he reaches a constant speed of 50 m/s. Which statement accurately describes his kinetic energy while falling?
A. His kinetic energy was positive at first, but it decreased to zero when he stopped accelerating
B. His kinetic energy increased quickly at first, then it increased at a constant rate
C. His kinetic energy increased while his speed increases, then it became constant
D. His energy would remain the same for the whole fall as long as he lost no mass

Answer 1

The correct statement that accurately describes the kinetic energy of the skydiver while falling is:

**C. His kinetic energy increased while his speed increased, then it became constant.**

Here's the reasoning:

- When the skydiver jumps out of the plane, he starts with an initial speed of 0 m/s, so his initial kinetic energy is also 0.
- As he accelerates (due to gravity) and his speed increases, his kinetic energy increases as well, since kinetic energy (KE) is given by the equation \( KE = \frac{1}{2} mv^2 \), where \( m \) is mass and \( v \) is velocity.
- Once he reaches terminal velocity (50 m/s in this case), he stops accelerating, and his speed becomes constant. At this point, his kinetic energy remains constant as long as his speed does not change.

Thus, option C best describes the change in kinetic energy of the skydiver during the fall.