Predicting Changes in Kinetic Energy Quick Check

Question

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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 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.

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.
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Answer 1

The correct response is:

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

This is accurate because as the skydiver's speed increases during free fall, his kinetic energy (KE) also increases. Kinetic energy is given by the formula \( KE = \frac{1}{2}mv^2 \), where \( m \) is mass and \( v \) is velocity. As the skydiver's speed increases from 20 m/s to 30 m/s and ultimately to 50 m/s, his kinetic energy increases. Once he reaches a constant speed (50 m/s) and no longer accelerates, his kinetic energy remains constant as well.