If you wanted to decrease the gravitational force between two objects what would you do

Name three different units of energy used to measure heat and describe what type of situations each is usually used.

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 experiment done in lab is repeated, using a ball that has unknown mass m. you plot your data in the form of f 2 versus m/l, with f in rev/s, m in kg, and l in m. your data falls close to a straight line that has slope 3.19 m/(kg · s2). use g = 9.80 m/s2 and calculate the mass m of the ball.