In a closed system, how does energy behave during a skydiver's fall?

In a closed system, how does energy behave during a skydiver's fall?

• A. Energy is conserved; potential energy decreases and kinetic increases, with a small amount converted to thermal energy by air resistance; total energy remains constant.
• B. Energy accelerates as the skydiver falls
• C. Energy disappears as heat only at terminal velocity
• D. Potential energy stays constant while kinetic increases

Answer: (A)

The situation tests how energy is conserved when non‑ideal forces are at play. As the skydiver falls, gravitational potential energy decreases because height is lost. That energy is transferred into kinetic energy, so the speed increases. But the air provides a drag force that does negative work, taking some of that mechanical energy and turning it into thermal energy in the air and the diver. If you include heat energy in the system, the total energy remains constant. That means energy is conserved overall, even though the mix of potential, kinetic, and thermal energy changes. At terminal velocity, the kinetic energy stops increasing, but gravity still feeds energy that ends up as heat through drag, so total energy is still conserved.

The situation tests how energy is conserved when non‑ideal forces are at play. As the skydiver falls, gravitational potential energy decreases because height is lost. That energy is transferred into kinetic energy, so the speed increases. But the air provides a drag force that does negative work, taking some of that mechanical energy and turning it into thermal energy in the air and the diver. If you include heat energy in the system, the total energy remains constant. That means energy is conserved overall, even though the mix of potential, kinetic, and thermal energy changes. At terminal velocity, the kinetic energy stops increasing, but gravity still feeds energy that ends up as heat through drag, so total energy is still conserved.