Name: _______________________
Gravitation Practice Test
Date: ___________ Period: _____
I. VOCABULARY
If the underlined word is used incorrectly, cross it out and replace it with the correct word.
1. The law of universal acceleration says: there is an repulsive force between any two masses.
2. Newton found that the force of gravity varies directly with the distance and inversely with the
square of the force.
3. When the distance between two objects is tripled, the force is one-fourth as strong.
4. Gravity is a very strong force, it is barely noticeable unless the masses are small.
5. Your weight on a planet depends on the shape and color of the planet.
II. FORCE OF GRAVITY DRAWINGS
6. Draw arrows to indicate the magnitude of the force of gravity acting between each pair of masses.
III. MULTIPLE CHOICE
7. Which of the following best explains why an
object has less weight on top of a mountain?
A
B
C
D
Because you are closer to space.
The atmosphere is lighter.
The mountain adds more mass.
The mountain adds more distance.
8. On a planet with twice the radius and twice
the mass of the earth, your weight would be
equal to your weight on earth times a factor of
A 1/4
B 2
C 1/2
D 4
IV. GRAVITY PROPORTION PROBLEMS
20 N
𝑚
9. What is the gravitational force on mass A from…
(a) mass B? (show work!)
(b) mass C? (show work!)
20 N
𝑚
𝑚
??𝑁
??𝑁
B
A
C
2𝑚
𝑚
4𝑚
Fremont Physics ©Kepple 2011
Gravitation – Page #6
10. What is the net force
on mass A?
11. In which direction will
mass A accelerate?
Gravitation Study Guide
MAJOR CONCEPTS:
 The law of universal gravitation states that
any two masses will attract each other.
 Gravity is a very weak force, it is barely
noticeable unless the mass involved is huge.
 The force of gravity is directly proportional
to mass and inversely proportional to the
square of distance.
 Your weight on a planet depends only upon
the mass and radius of the planet, not the
size of the planet.
 The force of gravity extends infinitely in all
directions, but it gets weaker with distance.
 Because the moon has tangential velocity, it
orbits Earth instead of crashing into it.
FORCE OF GRAVITY DRAWINGS
The force of gravity increases with mass and
decreases with distance. The length of the
arrow indicates the strength of the force. The
longer the arrow, the stronger the force.
FORCE OF GRAVITY PROPORTIONS
The relations within the
law of gravitation are…
FORCE and MASS
are DIRECT!
FORCE and DISTANCE
are INVERSE SQUARE!
STRONGER
(more mass)
2𝑚→
⬚
𝐹
⬚
2𝑟 →
⬚
𝐹
⬚
𝑚→
⬚
𝐹
⬚
𝑟→
⬚
𝐹
⬚
WEAKER
(more distance)
2
GRAVITATION PROPORTION PROBLEMS
If the force of gravity between two masses is
given, you can figure out the other forces.
Ex1. What is the force between masses A and B?
𝐹
20 N
𝑚
20 N
𝑀𝑚
𝑟
2
2
𝐹𝐴𝐵
2𝐹
2 20
40
𝑚
𝑚
??𝑁
2
Ex2. What is the force between masses B and C?
??𝑁
B
A
C
2𝑚
𝑚
3𝑚
𝐹
𝑀𝑚
𝑟
2 3
2 2
3
2
𝐹𝐵𝐶
3
𝐹
2
3
20
2
30