Aguitar string vibrates with a frequency of 256hz. what is the period of vibration

Ametal ball with a mass of 0.028 kg is dropped from rest at a height of 1.0 meters above the ground. assuming the energy in the ball is conserved, how much kinetic energy will the ball have when it is 0.5 meters above the ground?

A100 kg running back runs at 5m/s into a stationary linebacker. it takes 0.5 for the running back to be completely stopped

What is the measure of how much matter is in an object and that can be measured using a balance? a. height b. volume c. weight d. mass