Gravity

1. Newton's Law of gravitation states (in part) that the force between two masses is ...

• A. proportional to the square of the distance between them
• B. proportional to the sum of the masses
• C. inversely proportional to the square of the distance between them
• D. inversely proportional to the product of the masses

2. The force between two objects of mass M and m separated by a distance r is F. If the distance is decreased to r/4 and the mass M increased to 4M, the new force will be:

• A. F
• B. 4F
• C. 16F
• D. 64F

3. The gravitational field strength is defined as the ...

• A. force per unit distance
• B. force per unit mass
• C. acceleration of gravity
• D. acceleration per unit mass

4. The gravitational field in the region around the Earth is correctly described as ...

• A. circular
• B. polar
• D. uniform

5+6: Two objects of mass m and 2m are located at distances r and 2r from a planet as shown. 5. The ratio gravitational field strength at m is: gravitational field strength at 2m
• A. 2
• B. ½
• C. 4
• D. ¼

6. All three masses in the above diagram will be attracted together. Which mass moves with the largest initial acceleration?

• A. planet
• B. mass m
• C. mass 2m
• D. mass m and 2m have the same high acceleration

7. The diagram shows a planet and a moon . At approximately which point will the gravitational field strength between the planet and moon be zero? 8. Mars takes longer to orbit the Sun than the Earth. Which of these statements about Mars' orbit is true?

 I The circumference of Mars' orbit is longer than that of the Earth II Mars orbits at a slower velocity than the Earth III The centripetal force acting on Mars is smaller than that on the Earth

• A. I and II
• B. I and III
• C. II and III
• D. All three statements