Momentum, Hooke’s Law and Law of Universal Gravitation Assignment 1. Earth’s mass is approximately 81 times the mass of the Moon. If Earth exerts a gravitational
force of magnitude F on the Moon, the magnitude of the gravitational force of the Moon on Earth
is
1.
2.
3.
4.
F
F/81
9F
81F
2. A container of rocks with a mass of 65 kilograms is brought back from the Moon’s surface where
the acceleration due to gravity is 1.62 meters per second2. What is the weight of the container of
rocks on Earth’s surface?
1. 638 N
2. 394 N
3. 105 N
4. 65 N
3. The gravitational force of attraction between Earth and the Sun is 3.52 x 1022 N. Calculate the
mass of the Sun. [Show all work, including the equation and substitution with units.]
4.
As a meteor moves from a distance of 16 Earth radii to a distance
of 2 Earth radii from the center of Earth, the magnitude of the
gravitational force between the meteor and Earth becomes
1. 1/8 as great
2. 8 times as great
3. 64 times as great
4. 4 times as great
5. The net force on a planet is due primarily to the other planets and the Sun. By taking into
account all the forces acting on a planet, investigators calculated the orbit of each planet. A small
discrepancy between the calculated orbit and the observed orbit of the planet Uranus was noted. It
appeared that the sum of the forces on Uranus did not equal its mass times its acceleration, unless
there was another force on the planet that was not included in the calculation. Assuming that this
force was exerted by an unobserved planet, two scientists working independently calculated where
this unknown planet must be in order to account for the discrepancy. Astronomers pointed their
telescopes in the predicted direction and found the planet we now call Neptune.
a) What fundamental force is the author referring to in this passage as a force between planets?
b)
The diagram at right represents Neptune,
Uranus, and the Sun in a straight line.
Neptune is
x 1012 meters from Uranus.
Calculate the magnitude of the
interplanetary force of attraction between
Uranus and Neptune at this point. [Show all
work, including the equation and
substitution with units.]
c) The magnitude of the force the Sun exerts on Uranus is 1.41 x 1021 N. Explain how it is possible
for the Sun to exert a greater force on Uranus than Neptune exerts on Uranus.
6. A spring scale reads 20 N as it pulls a 5.0-kilogram mass across a table. What is the magnitude of
the force exerted by the mass on the spring scale?
1. 49 N
2. 20 N
3. 5.0 N
4. 4.0 N
7. The spring in a scale in the produce department of a supermarket stretches 0.025 meter when a
watermelon weighing 1.0x102 N is placed on the scale. The spring constant for this spring is
1. 3.2 x 105 N/m
2. 4.0 x 103 N/m
3. 2.5 N/m
4. 3.1 x 10-2 N/m
8.
The graph below represents the relationship between the force applied to a spring and spring
elongation for four different springs.
1.
2.
3.
4.
Which spring has the greatest spring constant?
A
B
C
D
9. A vertically hung spring has a spring constant of 150 N/m. A 2.00-kilogram mass is suspended
from the spring and allowed to come to rest.
Calculate the elongation of the spring produced by the suspended 2.00-kilogram mass. [Show all
work, including the equation and substitution with units.]
10. A 70-kilogram hockey player skating east on an ice rink is hit by a 0.1-kilogram hockey puck
moving toward the west. The puck exerts a 50-newton force toward the west on the player.
Determine the magnitude of the force that the player exerts on the puck during this collision.
11. A 0.149-kilogram baseball, initially moving at 15 meters per second, is brought to rest in 0.040
second by a baseball glove on a catcher’s hand. The magnitude of the average force exerted on the
ball by the glove is
1.
2.2 N
2.
2.9 N
3.
17 N
4.
56 N
12. A 0.45-kilogram football traveling at a speed of 22 meters per second is caught by an 84 kg
stationary receiver. If the football comes to rest in the receiver’s arms, the magnitude of the impulse
imparted to the receiver by the ball is
1.
2.
3.
4.
1800 N∙s
9.9 N∙s
4.4 N∙s
3.8 N∙s