What energy changes occur when a ball is dropped from rest and hits the ground?

What energy changes occur when a ball is dropped from rest and hits the ground?

• A. The energy is stored in the spring in the ball
• B. The energy remains as potential energy forever
• C. Energy dissipates as heat and sound due to friction
• D. Energy is created from nothing

Answer: (C)

Gravity gives the ball energy as it falls: its gravitational potential energy decreases while kinetic energy increases. When the ball hits the ground, the motion energy can’t stay as motion, so it changes into other forms. The impact deforms the ball and ground a bit, and the vibrations and rubbing at the contact produce sound, while friction inside the materials turns some energy into heat. That’s why energy ends up as heat and sound rather than staying as potential energy or being created anew. Energy is conserved overall, just transformed from one form to another, not stored in a spring inside the ball and not generated from nothing.

Gravity gives the ball energy as it falls: its gravitational potential energy decreases while kinetic energy increases. When the ball hits the ground, the motion energy can’t stay as motion, so it changes into other forms. The impact deforms the ball and ground a bit, and the vibrations and rubbing at the contact produce sound, while friction inside the materials turns some energy into heat. That’s why energy ends up as heat and sound rather than staying as potential energy or being created anew. Energy is conserved overall, just transformed from one form to another, not stored in a spring inside the ball and not generated from nothing.