Fact 1: Hitting an object causes the particles in that object to vibrate.

Fact 2: Frequency is the measurable rate of that vibration.

Given the two facts above, answer the question "what changes to the particles of an object when hit?" with the following options: 
- Temperature
 - frequency
 - Energy.
 - volume
 - molecules
 - density
 - energy
 - heat energy


 

  frequency       