Forces, Inertia and Gravity

Which of these can cause a moving object to change direction?

• inertia

• velocity

• force

• mass

What is gravitational force?

• the force that keeps people from moving

• the force of attraction between any two objects

• the force that makes inert objects start moving

• the only force that changes an object's velocity

Where is an object's center of gravity?

• the exact center of its mass

• the part that is closest to the Earth

• any part of any object, as long as it has mass

• all of the above

A paperclip and a computer are sitting on your desk. What is true about the gravitational force of these two objects.

• The paperclip attracts the computer with less gravitational force that the computer attracts the paperclip.

• The computer and the paperclip attract each other with equal gravitational force.

• The computer attraccts the paperclip with less gravitational force than the paperclip attracts the computer.

• There is no gravitational force between the paperclip and the computer.

Why don't we see the ground coming toward us?

• We have less gravitational force than the Earth

• We have more inertia than the Earth

• We have less mass than the Earth

• We are already standing on the Earth

It has very little inertia, so it stays in the sky and floats through space?

• It has very little inertia, so it stays in the sky and floats through space.

• It has a lot of mass, so it feels the Earth's gravitational force less than smaller objects do.

• It has more mass than the Earth, so it stays in one place while the Earth orbits it.

• It is too small to fall through the Earth's atmosphere and reach the Earth's surface.

Why is it impossible to "defy gravity"?

• There is no gravity.

• You can't defy gravity without going to another planet.

• Gravitational force exists every place where there are two objects.

• Nothing has enough force to resist gravity.