A ball is dropped and hits the ground but does not bounce back to its original height. What happened to the missing energy?
AIt was destroyed
BIt was converted to heat and sound when the ball hit the ground
CIt floated away into the air
DThere was no missing energy
The energy was not destroyed. When the ball hit the ground, some kinetic energy was converted into heat and sound, so less energy was available for the bounce.
Question 2 True / False
The total energy in a closed system always stays the same.
TTrue
FFalse
Answer: True
This is the law of conservation of energy. Energy can change forms and transfer between objects, but the total amount never increases or decreases.
Question 3 Short Answer
Where does the energy 'go' when you rub your hands together and they get warm?
Think about your answer, then reveal below.
Model answer: The kinetic energy of your moving hands is converted into heat energy.
Friction between your hands converts motion energy into thermal energy (heat), which is why your palms feel warmer.