Estimate my age in seconds 14 years old

When a spring is compressed, the energy changes from kinetic to potential. which best describes what is causing this change? work power gravitational energy chemical energy

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

The frequency of the fundamental of the guitar string is 320 hz. at what speed v do waves move along that string?