Field Forces

Why does an astronaut weigh less on the moon than on Earth?

• The astronaut has less mass on the moon.

• The astronaut is farther from Earth’s center when he or she is on the moon.

• The gravitational field strength is less on the moon’s surface than on Earth’s surface.

• The astronaut is continually in free fall because the moon orbits Earth.

When calculating the gravitational force between two extended bodies, you should measure the distance

• from the closest points on each body.

• from the most distant points on each body.

• from the center of each body.

• from the center of one body to the closest point on the other body.

The gravitational force between two masses is 27 N. What is the gravitational force if the distance between them is tripled?

• 3.0 N

• 9.0 N

• 13.5 N

• 4.5 N

Two small masses that are 5.0 cm apart attract each other with a force of 10.0 N. When they are 2.5 cm apart, these masses will attract each other with what force?

• 5.0 N

• 2.5 N

• 20.0 N

• 40.0 N

The gravitational force between two massive spheres

• is always an attraction.

• depends on how massive they are.

• depends inversely on the square of the distances between them.

• all of the above

A very massive object A and a less massive object B move toward each other under the influence of mutual gravitation. Which force, if either, is greater?

• The force on B

• The force on A

• Both forces are the same.

Suppose the gravitational force between two spheres is 20 N. If the magnitude of each mass doubles, what is the force between the masses?

• 5 N

• 10 N

• 40 N

• 80 N

According to Newton's laws, a rock and a pebble will fall with the same acceleration in a gravitational field because the gravitational force on each is _____.

• the same

• different, though the ratio of the force to the mass of each is the same

• none of the above

A man who weighs 300 N at Earth's surface stands on top of a very tall ladder so he is one Earth radius above Earth's surface. How much does he weigh?

• zero

• 150 N

• 300 N

• 600 N

• 75 N

An attracting force occurs between two charged objects when the charges are of

• unlike signs.

• like signs.

• equal magnitude.

• unequal magnitude.