Fact 1: Hitting an object causes the particles in that object to vibrate. Fact 2: By it's nature, a vibration is a frequency wave . Given the two facts above, what does hitting an object cause?

Possible answers: 1. frequency waves. 2. harmful substances. 3. Electrical energy. 4. chemical reaction. 5. friction. 6. Movement. 7. heat energy. 8. chemical changes.
The answer is:
1.