Two identical spheres (of equal mass) a distance of 10 meters apart exert a force of gravity of 0.00050 N on each other. What are their masses?

Your pendulum clock which advances 1.0 s for every complete oscillation of the pendulum is running perfectly on earth at a site where the magnitude of the acceleration due to gravity is 9.80 m/s2. you send the clock to a location on the moon where the magnitude of the acceleration due to gravity is 1.65 m/s2.

It is really hard for me right know

In which of the following is positive work done by a person on a suitcase