What is gravity?(20 points) 1. A force that pulls objects toward the center of Earth.

2. A force that pushes objects away from the center of Earth.

3. Energy that moves objects away from the center of Earth.

4. Energy that moves objects toward the center of Earth.

Two steel balls, each of mass m, are welded to a light rod of length l and negligible mass and are initially at rest on a smooth horizontal surface. a horizontal force of magnitude f is suddenly applied to the rod as shown. determine (a) the instantaneous acceleration a of the mass center g and (b) the corresponding rate at which the angular velocity of the assembly about g is changing with time.