Satellites and Space station questions

[F.B]

I really don't understand the universal gravitation chapters and the satellites one. It is sooo confusing. So can anyone help me with these questions.

1. Determine the magnitude of the apparent of a 56 kg student standing in an elevator when the elevator is experiencing an acceleration of (a) 3.2 m's^2 [down] and (b) 3.2 m/s^2 [Up].
I don't even know how to start this question. I don't even know what exactly they are looking for. So can anyone please help.

2. The ISS travels at an altitude of 450 km above the surface of the Earth.
(a) Determine the magnitude of the gravitational forces on a 64 kg astronaut at that altitude.
(b) What percentage of the astronauts Earths-bound weight is in the force in (a)?

I don't know how to start any of these questions. Can anyone please tell me step by step on how to do this please.

 

[Aneleh]

1. What do you feel happens when you are in an elevator and it moves up or down? Do you feel "lighter" or "heavier"? Start by drawing a free body diagram of the person with the acceleration due to the elevator and the acceleration due to the force of gravity. But it's not clear to me what exactly they are asking for, "the magnitude of the apparent" ?

2. a) Well you have the general equation for the Force of Gravity exerted on one mass by another, you just solve that.