Physics Exam 2. Ch. 9 – Flashcards
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In what sense does the Moon "fall"?
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It falls away from the straight path that it would follow if there were no forces acting on it.
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State Newton's law of universal gravitation in words. Then do the same with one equation.
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The force is proportional to the product of two masses and inversely proportional to the square of the distance between their centers: F ~ m1m2/d2.
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What is the magnitude of Earth's gravitational force on a 1-kg body at Earth's surface?
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10 N
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Each of the following diagrams shows a spaceship somewhere along the way between Earth and the Moon (not to scale); the midpoint of the distance is marked to make it easier to see how the locations compare. Assume the spaceship has the same mass throughout the trip (that is, it is not burning any fuel). Rank the five positions of the spaceship from left to right based on the strength of the gravitational force that Earth exerts on the spaceship, from strongest to weakest.
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Gravity follows an inverse square law with distance, which means the force of gravity between Earth and the spaceship weakens as the spaceship gets farther from Earth.
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The following diagrams show five pairs of asteroids, labeled with their relative masses (M) and distances (d) between them. For example, an asteroid with M=2 has twice the mass of one with M=1 and a distance of d=2 is twice as large as a distance of d=1. Rank each pair from left to right based on the strength of the gravitational force attracting the asteroids to each other, from strongest to weakest.
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M=2 d=1 M=2
M=1 d=1 M=2
M=1 d=1 M=1
M=1 d=2 M=2
M=1 d=2 M=1
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How does the force of gravity between two bodies change when the distance between them is doubled?
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The force decreases to ¼ of its initial value.
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Predict how the upward force exerted on the feet by the scale will compare to the weight of the person if the elevator is moving upward at a constant speed.
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The upward force on the feet will be equal to the weight.
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Predict how the upward force exerted on the feet by the scale will compare to the weight if the elevator is moving downward at a constant speed.
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The upward force on the feet will be equal to the weight.
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Predict how the upward force exerted on the feet by the scale will compare to the weight if the elevator is accelerating upward.
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The upward force on the feet will exceed the weight.
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Predict how the upward force exerted on the feet by the scale will compare to the weight if the elevator is accelerating downward.
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The upward force on the feet will be less than the weight.
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What happens to the force of attraction between two planets when the distance between them is doubled?
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The force decreases to one quarter.
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Would the springs inside a bathroom scale be more compressed or less compressed if you weighed yourself in an elevator that was accelerating upward? Downward?
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More compressed while accelerating upward, but less compressed while accelerating downward
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Why are occupants of the International Space Station weightless?
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They are in free fall.
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Which of the following quantities represent mass?
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0.34 g
120 kg
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Which of the following quantities would be acceptable representations of weight?
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Weight is a force and is measured in newtons (or kilonewtons, meganewtons, etc.) or in pounds (or tons, megatons, etc.).
12.0 lbs
1600 kN
899 MN
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The gravitational field on the surface of the earth is stronger than that on the surface of the moon. If a rock is transported from the moon to the earth, which properties of the rock change?
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weight only
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An object is lifted from the surface of a spherical planet to an altitude equal to the radius of the planet. As a result, which of the following changes in the properties of the object take place?
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mass remains the same; weight decreases
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If acceleration due to gravity on the earth is g, which formula gives the acceleration due to gravity on Loput?
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g=5.6/1.7^2
Name Mass ( Mearth) Radius ( Rearth)
Tehar 2.1 0.80
Loput 5.6 1.7
Cremury 0.36 0.30
Suven 12 2.8
Pentune 8.3 4.1
Rams 9.3 4.0
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If the acceleration due to gravity on the earth is 9.8 m/s2, what is the acceleration due to gravity on Rams?
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5.7 m/s2
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Which planet should Punch travel to if his goal is to weigh in at 118 lb? Refer to the table of planetary masses and radii given to determine your answer.
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Pentune
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After Punch Taut travels to Pentune, what actually happens to his mass and his weight?
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mass remains the same; weight decreases
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When is your weight measured as mg?
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For a non-accelerating mass near the surface of Earth
