Question

A skydiver jumps out of a plane and begins to accelerate. His speed increases to 20 m/s, then 30 m/s. His acceleration slows until he reaches a constant speed of 50 m/s. Which statement accurately describes his kinetic energy while falling?(1 point) Responses His kinetic energy was positive at first, but it decreased to zero when he stopped accelerating. His kinetic energy was positive at first, but it decreased to zero when he stopped accelerating. His kinetic energy would remain the same for the whole fall as long as he lost no mass. His kinetic energy would remain the same for the whole fall as long as he lost no mass. His kinetic energy increased quickly at first, then it increased at a constant rate. His kinetic energy increased quickly at first, then it increased at a constant rate. His kinetic energy increased while his speed increases, then it became constant. His kinetic energy increased while his speed increases, then it became constant.

Answer 1

To analyze the kinetic energy of the skydiver, we can use the formula for kinetic energy (KE):

\[ KE = \frac{1}{2} mv^2 \]

where \( m \) is the mass of the skydiver and \( v \) is his velocity.

1. While the skydiver is accelerating: As the skydiver falls and his speed increases from 20 m/s to 30 m/s, his kinetic energy increases because velocity is squared in the equation. This means even a small increase in velocity results in a larger increase in kinetic energy.

2. At terminal velocity: When the skydiver reaches a constant speed of 50 m/s, his kinetic energy reaches a certain value and remains constant as long as he does not lose any mass or change speed.

Based on this understanding, the most accurate statement is:

"His kinetic energy increased while his speed increases, then it became constant."

This captures the essence of how kinetic energy changes as the skydiver's speed increases and then remains constant at terminal velocity.