A ball is dropped from rest. Ignoring air resistance, as it falls its
Correct answer: B. potential energy converts into kinetic energy with the total unchanged
- A. total mechanical energy increases
- B. potential energy converts into kinetic energy with the total unchanged
- C. kinetic energy converts into potential energy
- D. total mechanical energy decreases
Explanation
Gravity is a conservative force, so in the absence of air resistance the sum of kinetic and potential energy stays constant while potential energy is steadily converted into kinetic energy. With air resistance included the total mechanical energy would fall, the loss appearing as heat. Energy is never created, so the total cannot increase.
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About Potential Energy
Potential energy is energy stored because of position or configuration, including gravitational potential energy near Earth's surface and elastic energy in a stretched or compressed spring. Questions use changes in potential energy and conservation of mechanical energy, while distinguishing a chosen reference level from an absolute zero of energy.
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