Which best explains why astronauts appear weightless when they are in a space shuttle orbiting earth? they are falling toward earth at the same rate as the space shuttle. they are falling toward earth at a faster rate than the space shuttle. they are too far from earth to experience gravity. they are too far from earth to experience air resistance.

 Hello there!

When the astronauts are in orbit, they are too far from Earth to experience enough gravity, this is why they are "weightless"

Non the less, is not like "there is no gravity there", gravity is what keeps the space shuttle in orbit, the astronauts "appear" weightless, but they aren't, they still have mass, and still are being affected by gravitational forces, but now the gravitational force from the earth is depreciable, and contrasted a little bit by other gravitational forces.

a and b sometimes have a positive value

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.