Circular Motion and Gravitation

Centripetal force, created by swinging something in a circle, acts in a direction--

• along the path of motion

• away from the center of the circle

• toward the center of the circle

• tangent to the circle

A 10kg car travels at a constant speed of 20.0 m/s around a horizontal circular track. Which diagram correctly represent the direction of the car's velocity (v) and the direction of the centripetal force (Fc) acting on the car at a particular moment?

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How does the gravitational force the Earth exerts on the sun compare to the gravitational force the sun exerts on the Earth?

• The gravitational force the sun exerts on the Earth is larger

• The gravitational force the Earth exerts on the sun is larger

• Their gravitational forces are equal

• There is not enough information

Which of these best describes why your weight (on Earth) would change on another planet?

• Dehydration effects on different planets change weight.
• In general, the smaller the planet, the greater weight
• Different planets have different gravitational pulls
• Weight does not change, no matter where you are.

Complete the following statement: The farther away two planets are the _______ the gravitational force between them.

• more
• same
• dosen't matter
• less

Gravity on moon is less than the gravity on earth because

• a. moon's mass is less

• b. moon's mass is more

• c. moon's mass is equal to Earth

• d. moon has no mass

Calculate the gravitational force between two physics students who each are 70kg, sitting in the same class, separated by a distance of .5 m.

• 6.5 x 10^-7 N

• 1.3 x 10^-6 N

• 3.3 x 10^-7 N

• 1.5 x 10⁶ N

A car is rounding a curve as shown in the diagram. Which arrow correctly shows the direction of the centripetal force keeping the car in circular motion?

• A

• B

• C

• D

This picture was taken form the International Space Station. Centripetal Force keeps the space station in orbit.

• True

• False

Why is the gravitational force the Earth exerts on the Moon the same as the gravitational force the Moon exerts on the Earth?

• Because objects at rest tend to stay at rest and objects in constant motion stay in constant motion unless an external, unbalanced force, acts upon it.

• Because the moon experiences an acceleration in the presence of an unbalanced force from the earth.

• Because for every action force, this is an equal and opposite reaction force.

• The Law of Inertia