Universal Gravitation

Physics Universal Gravitation Study Guide

1. 
   The discovery of “Universal Gravitation” is associated with:
   

A. Robert Hook B. Isaac Newton

C. James Joule D. Max Plank

E. Henry Cavendish

2. The discovery of the magnitude of ‘G’ is associated with

A. Robert Hook B. Isaac Newton

C. James Joule D. Max Plank

E. Henry Cavendish

3. As the distance between the centers of mass increases, gravitational force

A. increases.

B. decreases.

C. remains the same.

D. it depends on the mass of the objects.

4. As the mass of the objects increases, gravitational force

A. increases.

B. decreases.

C. remains the same.

D. it depends on the distance between the objects.

5. An apple hangs on a tree on the Earth. Which of the following is correct?

1. 
   The force on the apple is greater than the force on the Earth because the Earth is more massive.
   
2. 
   The force on the Earth is greater than the force on the apple because the Earth is more massive.
   
3. 
   The force on the apple is less than the force on the Earth because the tree is supporting the apple.
   
4. 
   The forces on the apple and Earth are equal.
   
5. 
   The forces on the apple and the Earth are zero because they are not touching each other.
   

6. A rocket moves away from the surface of Earth. As the distance from the center of the planet increases, what happens to the force of gravity on the rocket?

A. The force increases as the distance becomes greater.

B .The force increases as the mass of the rocket decreases.

C. The force doesn’t change.

D. The force becomes zero after the rocket loses the contact with Earth

E. The force decreases as the distance from earth increases.

7. Two objects are attracted to each other by a gravitational force F. If the distance between the objects is doubled, what is the new gravitational force between the objects in terms of F?

A. 4 F B. 9 F C. 16 F

D. 1/9 F E. 1/4 F


0.5r

m

m

8. Two objects are attracted to each other by a

m

m
gravitational force F. If the distance between the

objects is halved, what is the new gravitational force

between the objects in terms of F? r

9. An object with a mass of 60 kg measured on Earth is taken to the Moon. What is the mass of the object on the Moon’s surface if the acceleration due to gravity on Moon is one-sixth of that on Earth?

A. 6 kg B. 10 kg C. 12 kg D. 60 kg E. 600 kg

10. A spacecraft starts on Earth is moving to the moon. Which of the following is correct about the gravitational force on the spacecraft due to Earth’ attraction?

1. 
   The force becomes zero when the spacecraft is half way to the moon
   
2. 
   The force becomes zero when the spacecraft is close to the surface of the moon
   
3. 
   The spacecraft is never beyond the Earth’s gravitational attraction
   
4. 
   The force becomes zero when the spacecraft land on the surface of the moon
   

11. A hypothetical planet has a mass similar to the Earth’s mass and approximately twice the radius. What is the acceleration due to gravity on the planet in terms of the acceleration on the Earth?

1. 
   4 g
   
2. 
   2 g
   
3. 
   ½ g
   
4. 
   ¼ g
   

12. The acceleration due to gravity on Jupiter is 2.5 times what it is on earth. An object of mass 10 kg is taken to Jupiter. What is its mass on Jupiter?

1. 
   10 kg
   
2. 
   25 kg
   
3. 
   10 N
   
4. 
   25 N
   

13. Two objects gravitationally attract each other. If the distance between them doubles, the gravitational force between them

1. 
   quadruples.
   
2. 
   doubles.
   
3. 
   is cut in half.
   
4. 
   is cut to one-fourth.
   

14. A spacecraft starts on Earth is moving to Mars. Which of the following is correct about the gravitational force on the spacecraft due to Earth’ attraction?

1. 
   The force becomes zero when the spacecraft is half way between the planets
   
2. 
   The force becomes zero when the spacecraft is closer to the surface of Mars
   
3. 
   The spacecraft is never beyond the Earth’s gravitational attraction
   
4. 
   The force becomes zero when the spacecraft land on the surface of Mars
   

15. The earth’s orbit around the sun is approximately circular. What is the direction of the net force on the earth?

1. 
   Towards the sun.
   
2. 
   In the direction of its velocity.
   
3. 
   Opposite the direction of its velocity.
   
4. 
   Away from the sun.
   

16. The moon moves in an approximately circular path around the earth at an approximately constant speed. Compare the directions of the moon’s velocity and acceleration vectors.

1. 
   Both vectors point in the same direction.
   
2. 
   The vectors point in opposite directions.
   
3. 
   The vectors are perpendicular.
   
4. 
   The question is meaningless, since acceleration is zero.