Explain a physics topic? Help

A spaceship is in orbit around the earth at an altitude of 12,000 miles. Which of the following statements best explains why the astronauts experience “weightlessness?”

ANSWER: The spaceship is in free fall and its floor cannot press upwards on the astronauts


Hi, I just do not know how to explain this. Physics is really nice to learn but some of the concepts were taught fast and I do not think that I comprehend a lot of them. Can someone explain why this answer is right? What equation or concept explains this?

This can be a tricky topic to understand. So this is the way I teach it to students:

When we think of someone floating space, are they really floating? Things float because something pushes up on them. A helium balloon is lighter than air, so when you let go... it floats.

In space there is nothing pushing UP, instead there is a very weak force of gravity pulling down.

So now lets think of weightlessness. Have you every been in a car on a hill or a theme park ride that made you feel weightless? I hope so or else this might not make sense.

As you go up a hill or a ride, you sink into your seat because you are being pushed up. This is why you "sink". Then at just the right moment, (at the top of a hill for example) the thing that is pushing you, like a seat, is moving at the same speed you are. This means it is no longer pushing you. When you are not being pushed you feel weightless. Then gravity kicks in and pulls you down back into your seat. Now that your butt is in the seat you no longer feel weightless because you are pushing on the seat.

So in space, the astronauts are basically falling at the same speed of their ship. This happens because the force of gravity is so small at the high of altitude, but it is still there. So they can "float" for a very long time. The closer they come to earth to more gravity attracts them and the faster they fall.