13 UCM Gravity
13 UCM Gravity
13 UCM Gravity
UCM-Gravity
1. A space probe is launched into space from Earth’s surface. Which graph represents the relationship between the
magnitude of the gravitational force exerted on Earth by the space probe and the distance between the space probe
and the center of Earth?
2. The diagram shows two bowling balls, A and B, each 6. A container of rocks with a mass of 65 kilograms is
having a mass of 7 kilograms, placed 2 meters apart. brought back from the Moon’s surface where the ac-
celeration 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
What is the magnitude of the gravitational force 3. 105 N
exerted by ball A on ball B? 4. 65 N
1. 8.17 × 10-9 N
2. 1.63 × 10-9 N 7. The graph below represents the relationship between
3. 8.17 × 10-10 N gravitational force and mass for objects near the
4. 1.17 × 10-10 N surface of Earth.
4. Earth’s mass is approximately 81 times the mass of The slope of the graph represents the
the Moon. If Earth exerts a gravitational force of 1. acceleration due to gravity
magnitude F on the Moon, the magnitude of the 2. universal gravitational constant
gravitational force of the Moon on Earth is 3. momentum of objects
1. F 4. weight of objects
2. F/81
3. 9F 8. A person weighing 785 newtons on the surface of
4. 81F Earth would weigh 298 newtons on the surface of
Mars. What is the magnitude of the gravitational
5. An object weighs 100 newtons on Earth’s surface. field strength on the surface of Mars?
When it is moved to a point one Earth radius above 1. 2.63 N/kg
Earth’s surface, it will weigh 2. 3.72 N/kg
1. 25 N 3. 6.09 N/kg
2. 50 N 4. 9.81 N/kg
3. 100 N
4. 400 N
Page 64 UCM.B1 APlusPhysics: UCM-Gravity
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UCM-Gravity
Base your answers to questions 9 through 11 on the passage and data table below.
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 ap-
peared 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 dis-
crepancy. Astronomers pointed their telescopes in the predicted direction and found the planet we now call Neptune.
9. What fundamental force is the author referring to in this passage as a force between planets?
10. The diagram at right represents Neptune, Uranus, and the Sun in a
straight line. Neptune is 1.63 × 1012 meters from Uranus.
11. The magnitude of the force the Sun exerts on Uranus is 1.41 × 1021 newtons. Explain how it is possible for the Sun
to exert a greater force on Uranus than Neptune exerts on Uranus.
12. When Earth and the Moon are separated by a dis- 13. An astronaut weighs 8.00 × 102 newtons on the sur-
tance of 3.84 × 108 meters, the magnitude of the grav- face of Earth. What is the weight of the astronaut
itational force of attraction between them is 2.0 × 1020 6.37 × 106 meters above the surface of Earth?
newtons. What would be the magnitude of this grav- 1. 0.00 N
itational force of attraction if Earth and the Moon 2. 2.00 × 102 N
were separated by a distance of 1.92 × 108 meters? 3. 1.60 × 103 N
1. 5.0 × 1019 N 4. 3.20 × 103 N
2. 2.0 × 1020 N
3. 4.0 × 1020 N
4. 8.0 × 1020 N
APlusPhysics: UCM-Gravity UCM.B1 Page 65
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UCM-Gravity
Base your answers to questions 14 and 15 on the informa- 18. A 5.0-kilogram sphere, starting from rest, falls freely
tion and table below. 22 meters in 3.0 seconds near the surface of a plan-
et. Compared to the acceleration due to gravity near
The weight of an object was determined at five different Earth’s surface, the acceleration due to gravity near
distances from the center of Earth. The results are shown the surface of the planet is approximately
in the table below. Position A represents results for the 1. the same
object at the surface of Earth. 2. twice as great
3. one-half as great
4. four times as great
UCM-Gravity
Base your answers to questions 21 and 22 on the informa- 24. Two physics students have been selected by NASA
tion below. [Show all work, including the equation and to accompany astronauts on a future mission to the
substitution with units.] Moon. The students are to design and carry out a
simple experiment to measure the acceleration due to
Io (pronounced “EYE oh”) is one of Jupiter’s moons dis- gravity on the surface of the Moon.
covered by Galileo. Io is slightly larger
than Earth’s Moon. Describe an experiment that the students could con-
duct to measure the acceleration due to gravity on the
The mass of Io is 8.93 × 1022 kilograms Moon. Your description must include:
and the mass of Jupiter is 1.90 × 1027 • the equipment needed
kilograms. The distance between the • what quantities would be measured using the
centers of Io and Jupiter is 4.22 × 108 meters. equipment
• what procedure the students should follow in
21. Calculate the magnitude of the gravitational force of conducting their experiment
attraction that Jupiter exerts on Io. • what equations and/or calculations the students
would need to do to arrive at a value for the ac-
celeration due to gravity on the Moon.
UCM-Gravity
26. A 25-kilogram space probe fell freely with an accel- 32. A 1200-kilogram space vehicle travels at 4.8 meters
eration of 2 meters per second2 just before it landed per second along the level surface of Mars. If the
on a distant planet. What is the weight of the space magnitude of the gravitational field strength on the
probe on that planet? surface of Mars is 3.7 newtons per kilogram, the mag-
1. 12.5 N nitude of the normal force acting on the vehicle is
2. 25 N 1. 320 N
3. 50 N 2. 930 N
4. 250 N 3. 4400 N
4. 5800 N
27. The acceleration due to gravity on the surface of
planet X is 19.6 meters per second2. If an object on 33. What is the weight of a 2.00-kilogram object on the
the surface of this planet weighs 980 newtons, the surface of Earth?
mass of the object is 1. 4.91 N
1. 50 kg 2. 2.00 N
2. 100 kg 3. 9.81 N
3. 490 N 4. 19.6 N
4. 908 N
34. A 2.0-kilogram object is falling freely near Earth’s
28. What is the acceleration due to gravity at a location surface. What is the magnitude of the gravitational
where a 15-kilogram mass weighs 45 newtons? force that Earth exerts on the object?
1. 675 m/s2 1. 20 N
2. 9.81 m/s2 2. 2.0 N
3. 3.00 m/s2 3. 0.20 N
4. 0.333 m/s2 4. 0.0 N
29. As an astronaut travels from the surface of Earth 35. Calculate the magnitude of the centripetal force act-
to a position that is four times as far away from the ing on Earth as it orbits the Sun, assuming a circular
center of Earth, the astronaut’s orbit and an orbital speed of 3.00 × 104 meters per
1. mass decreases second. [Show all work, including the equation and
2. mass remains the same substitution with units.]
3. weight increases
4. weight remains the same 36. On a small planet, an astronaut uses a vertical force
of 175 newtons to lift an 87.5-kilogram boulder at
30. A satellite weighs 200 newtons on the surface of constant velocity to a height of 0.350 meter above
Earth. What is its weight at a distance of one Earth the planet’s surface. What is the magnitude of the
radius above the surface of Earth? gravitational field strength on the surface of the
1. 50 N planet?
2. 100 N 1. 0.500 N/kg
3. 400 N 2. 2.00 N/kg
4. 800 N 3. 9.81 N/kg
4. 61.3 N/kg
31. A 2.00-kilogram object weighs 19.6 newtons on
Earth. If the acceleration due to gravity on Mars is 37. Calculate the magnitude of the average gravitational
3.71 meters per second2, what is the object’s mass on force between Earth and Moon. [Show all work,
Mars? including the equation and substitution with units.]
1. 2.64 kg
2. 2.00 kg
3. 19.6 N
4. 7.42 N
Page 68 UCM.B1 APlusPhysics: UCM-Gravity
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38. Which graph represents the relationship between the 40. At a certain location, a gravitational force with a
magnitude of the gravitational force exerted by Earth magnitude of 350 newtons acts on a 70-kilogram as-
on a spacecraft and the distance between the center of tronaut. What is the magnitude of the gravitational
the spacecraft and center of Earth? [Assume constant field strength at this location?
mass for the spacecraft.] 1. 0.20 kg/N
2. 5.0 N/kg
3. 9.8 m/s2
4. 25,000 N•kg
UCM-Gravity
Base your answers to questions 43 through 45 on the information below and on your knowledge
of physics. [Show all work, including the equation and substitution with units.]
Pluto orbits the Sun at an average distance of 5.91 × 1012 meters. Pluto’s diameter is 2.30
× 106 meters and its mass is 1.31 × 1022 kilograms.
Charon orbits Pluto with their centers separated by a distance of 1.96 × 107 meters.
Charon has a diameter of 1.21 × 106 meters and a mass of 1.55 × 1021 kilograms.
43. Calculate the magnitude of the gravitational force of attraction that Pluto exerts on
Charon.
45. State the reason why the magnitude of the Sun’s gravitational force on Pluto is greater than the magnitude of the
Sun’s gravitational force on Charon.