Newton’s Law of Universal Gravitation
At each labeled point above, find the weight of an 80 kg person, the acceleration due to gravity felt by the
person, and the force of attraction between the person and the earth. Each point is exactly 1 “earth’s radius”
away from the previous point, except for point E, which is 10,000 m above the earth’s surface.
1. Two students are sitting 1.50 m apart. One student has a mass of 70.0 kg and the other has a mass of
52.0 kg. What is the gravitational force between them?
2. The gravitational force between two objects that are 0.21 m apart is 3.2 × 10‐6 N. If the mass of one
object is 55 kg what is the mass of the other object?
3. If two objects, each with a mass of 200 kg, produce a gravitational force between them of 3.7 × 10‐6 N.
What is the distance between them?
4. Calculate the gravitational force on a 6.50 × 102 kg that is 4.15 × 106 m above the surface of the Earth?
5. The planet Jupiter has a mass of 1.9 × 1027 kg and a radius of 7.2 × 107 m. Calculate the acceleration due
to gravity on Jupiter.
6. The force of attraction between m1 and m2 is 26 N. What will this force become if m2 is tripled and the
distance between it and m1 is halved?
7. The force of gravity between two masses was 14 N when they were 10 m apart. The distance between
them was changed and the force became 56 N. How far apart were they then?
8. What gravitational force does the moon produce on the Earth is their centers are 3.88 × 108 m apart and
the moon has a mass of 7.34 × 1022 kg?
9. Calculate the gravitational attraction between a proton of mass 1.67 × 10-27 kg and an electron of mass
9.11 × 10-31 kg if they are 5 × 10-11 m apart (as they are in a normal hydrogen atom).
10. If the gravitational force between objects of equal mass is 2.30 × 10‐8 N when the objects are 10.0 m
apart, what is the mass of each object?
11. One object has a mass of 2.5 kg and the other is 12.5 kg. The gravitational force between them is 1.3 ×
10–10 N. How far apart are they?
12. What is the gravitational force on a 70.0 kg that is 6.38 × 106 m above the Earth’s surface?
13. An object weighs 100 N on the surface of the earth. Find its weight if it was 6.38 × 106 m above the
surface?
14. The planet Saturn has mass of 5.67 × 1026 kg and radius of 6.3 × 107 m. Find the acceleration due to
gravity on Saturn.
15. The Earth’s moon has a mass of 7.35 × 1022 kg. The radius of the moon is 6.96 × 109 m. Calculate the
acceleration due to gravity on the moon.
16. The force of gravity on a 60 kg woman is 588 N. The woman also exerts a gravitational force on the
Earth. How large a force is this?
17. The force of gravity between A and B is 100 N. When the mass of B is doubled and the distance
between it and A is quadrupled, what is the new force?
18. The force of gravitational attraction between two masses is 36 N. What will be the force if one mass is
doubled and the distance between them is tripled?
19. Three objects A, B, C are placed 50.0 cm apart along a straight line. A and B have a mass of 10.0 kg,
while C has a mass of 15.0 kg. What is the net force on B due to A and C?