When tuning his guitar, a music student notices that the string is not vibrating at the desired frequency of 120 Hz, so he tightens the string by 15.5% to get this frequency. At what frequency was the string vibrating when he first started the tuning process

Africtionless piston-cylinder contains 50 l of saturated liquid r-134a. the piston has a mass and an area resulting in an applied pressure of 500 kpa on the refrigerant. the refrigerant is now heated until its temperature rises to 70∘c. calculate the work (in kj) done during this process.

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?

The mass of a bowling ball is 10 kg and the mass of a ping pong ball is 0.015 kg. if the two objects are 5 meters apart, what is the gravitational force ?