How do I find the answers

The geological theory that states that pieces of earth's lithosphere are in constant slow motion is the theory of plate tectonics.

There was no intial y-momentum so the net final y-momentum must also be 0. they can have final velocities in the y-direction

Not sure but i think it's b.

Gravity, from the center of mass of the box, extending downward normal force, from the floor under the box, extending upward, equal to gravity push force, acting at a point on the box, extending in the direction of motion friction, acting at any point on the box directly opposite the push, extending directly opposite to the motion