Joe has a mass of 50 kg and Sally has a mass of 30 kg. They sit in class with a separation of 0.5 meters. Find the gravitational attraction between Joe and Sally.

Answer 1

Use Newton's universal law of gravity, with the constant G

F = G*m1*m2/R^2

R should be in meters, and masses in kg, if you want the force in Newtons. Look up the value of G if your don't know it. It is NOT the same as g.