Physics Chapters 12 Thru 14 (Due Jan

Physics Chapters 12 thru 14 (Due Jan. 18, Test Jan. 22)

Multiple Choice

Identify the choice that best completes the statement or answers the question.

____1.Newton had the insight to see that the _____.

a. / moon is moving
b. / moon orbits Earth
c. / force on the moon has the same nature as the force on an apple
d. / moon always keeps one side toward Earth
e. / none of the above

____2.Newton hypothesized that the moon _____.

a. / is a projectile
b. / is falling around Earth
c. / has tangential velocity that prevents it from falling into Earth
d. / is actually attracted to Earth
e. / all of the above

____3.Newton reasoned that the gravitational attraction between Earth and the moon must be _____.

a. / reduced by distance
b. / independent of distance
c. / directly proportional to distance
d. / the same at all distances
e. / all of the above

____4.If the mass of Earth increased, with no change in radius, your weight would _____.

a. / stay the same
b. / decrease
c. / increase also

____5.If the radius of Earth decreased, with no change in mass, your weight would _____.

a. / not change
b. / increase
c. / decrease

____6.If Earth's mass decreased to one half its original mass, with no change in radius, then your weight would _____.

a. / stay the same
b. / decrease to one half your original weight
c. / decrease to one quarter your original weight
d. / none of the above

____7.The gravitational force between two massive spheres

a. / is always an attraction.
b. / depends on how massive they are.
c. / depends inversely on the square of the distances between them.
d. / all of the above

____8.A very massive object A and a less massive object B move toward each other under the influence of mutual gravitation. Which force, if either, is greater?

a. / The force on B
b. / The force on A
c. / Both forces are the same.

____9.Two objects move toward each other because of gravitational attraction. As the objects get closer and closer, the force between them _____.

a. / remains constant
b. / decreases
c. / increases

____10.Gravitational forces are the weakest forces found in nature. Because of this _____.

a. / the gravitational effect between a pencil and Earth cannot be seen
b. / there is no gravitational force between two 1-kg masses
c. / gravitational forces that are easily observed involve one or more large masses
d. / there is no movement between two 1-kg masses located near each other in space
e. / gravitational effects occur only when a large mass is involved

____11.Suppose the gravitational force between two massive spheres is 100 N. If the distance between the spheres is doubled, what is the force between the masses?

a. / 400 N
b. / 200 N
c. / 100 N
d. / 50 N
e. / 25 N

____12.By noticing that Uranus's orbit is perturbed and by using the law of gravitation, two astronomers independently discovered _____.

a. / Neptune
b. / exceptions to the law of gravitation
c. / the law of gravitation fails at large distances
d. / Uranus has several moons

____13.The force of gravity acting on you will increase if you _____.

a. / stand on a planet with a radius that is shrinking
b. / burrow deep inside the planet
c. / both A and B
d. / none of the above

____14.The force of gravity on you is greatest when you are standing _____.

a. / far above Earth's surface
b. / just above Earth's surface
c. / on Earth's surface

____15.The reason the moon does not fall into Earth is that _____.

a. / Earth's gravitational field at the moon is weak
b. / the moon has a sufficiently large orbital speed
c. / gravitational pull of other planets keeps the moon up
d. / the moon has less mass than Earth
e. / none of the above

____16.A lunar month is about 28 days. If the moon were closer to Earth than it is now, the lunar month would be _____.

a. / more than 28 days
b. / unchanged at 28 days
c. / less than 28 days

____17.A hollow spherical planet is inhabited by people who live inside it, where the gravitational field is zero. When a very massive space ship lands on the planet's surface, the gravitational field inside the planet is _____.

a. / nonzero, directed away from the spaceship
b. / still zero
c. / nonzero, directed toward the spaceship

____18.Each of us weighs a tiny bit less on the ground floor of a skyscraper than we do on the top floor. One reason for this is that _____.

a. / the gravitational field is shielded inside the building
b. / the mass of the building attracts you upward slightly
c. / both A and B
d. / none of the above

____19.A planet has half the mass of the Earth and half the radius. Compared to its weight on Earth, an apple on this planet would weigh _____.

a. / twice as much
b. / one-fourth as much
c. / half as much
d. / the same
e. / zero

____20.Consider the gravitational force between Earth and a meteor in outer space. If the meteor moves so its distance from the Earth's center doubles, the gravitational force on the meteor will be _____.

a. / one quarter
b. / half
c. / double
d. / quadruple
e. / eight times greater

____21.Which is greater, the gravitational force between Earth and the moon, or the force between Earth and the sun?

a. / Earth–moon
b. / equal
c. / Earth–sun

____22.Jupiter has more than 300 times the mass of Earth. Yet on Jupiter's surface an object weighs only about 3 times as much as it would on Earth. The explanation to this involves Jupiter's _____.

a. / high density
b. / greater distance from the sun
c. / large radius

____23.If you stood atop a ladder on Earth that was as tall as Earth's radius (so you were twice as far from Earth's center) your weight atop the ladder would be _____.

a. / one-eighth its normal value
b. / one-quarter its normal value
c. / half its normal value
d. / none of the above

____24.Why did Newton think there was a force acting on the moon?

a. / Because the moon always keeps one side toward Earth
b. / Because the moon moves in a curved path
c. / Because there is no air on the moon
d. / Because the moon is moving
e. / all of the above

____25.Since Earth is attracted to the sun, why doesn't it fall into the sun?

a. / Because it has too much mass to move toward the sun
b. / Because it has sufficient tangential velocity
c. / Because there is an equal force holding it away from the sun
d. / Because it has too much inertia to move toward the sun
e. / all of the above

____26.A 560-N woman stands on top of a very tall ladder so she is one Earth radius above Earth's surface. How much does she weigh?

a. / zero
b. / 140 N
c. / 280 N
d. / 560 N
e. / none of the above

____27.Suppose the gravitational force between two masses is 70 N. If the magnitude of one of the masses halves, what is the force between the masses?

a. / 280 N
b. / 140 N
c. / 70 N
d. / 35 N
e. / 18 N

____28.Suppose the gravitational force between two spheres is 70 N. If the distance between the spheres is halved, what is the force between the masses?

a. / 17.5 N
b. / 35 N
c. / 70 N
d. / 140 N
e. / 280 N

____29.Suppose the gravitational force between two spheres is 30 N. If the magnitude of each mass doubles, what is the force between the masses?

a. / 8 N
b. / 15 N
c. / 30 N
d. / 60 N
e. / 120 N

____30.If the mass of Earth increased, with no change in radius, your weight would _____.

a. / increase also
b. / stay the same
c. / decrease

____31.If the radius of Earth decreased, with no change in mass, your weight would _____.

a. / decrease
b. / increase
c. / not change

____32.According to Newton's laws, a rock and a pebble will fall with the same acceleration in a gravitational field because the gravitational force on each is _____.

a. / the same
b. / different, though the ratio of the force to the mass of each is the same
c. / none of the above

____33.The force of gravity on you is greatest when you are standing _____.

a. / just below Earth's surface
b. / on Earth's surface
c. / just above Earth's surface

____34.The value of the acceleration due to gravity, g, _____.

a. / depends on the universal gravitational constant, G
b. / depends on the mass of Earth
c. / is different on different planets
d. / depends on the radius of Earth
e. / all of the above

____35.We can tell if a gravitational force exists in a region of space if _____.

a. / we disturb a pendulum and it starts swinging
b. / we let go of a ball and it starts to move
c. / a force exists on a mass placed there
d. / we can weigh ourselves
e. / all of the above

____36.Gravitational field lines show the _____.

a. / direction of the field at each point
b. / direction of the force on any mass
c. / direction a mass would be accelerated
d. / strength of the field
e. / all of the above

____37.Compared to the gravitational field on the surface of Earth, the gravitational field well below Earth's surface is _____.

a. / larger
b. / smaller
c. / the same

____38.The gravitational field strength at the center of Earth is _____.

a. / the same as on the surface
b. / smaller than on the surface but still larger than zero
c. / zero
d. / large

____39.If you were to weigh yourself in an elevator that is accelerating upward, compared to your ordinary weight you would weigh _____.

a. / more
b. / less, but more than zero
c. / the same
d. / zero

____40.If you were to weigh yourself in an elevator that is in free fall, compared to your ordinary weight, you would weigh _____.

a. / more
b. / the same
c. / less, but more than zero
d. / zero

____41.If you drop a stone into a hole drilled all the way to the other side of Earth, the stone will _____.

a. / speed up until it gets to the center of Earth
b. / slow down until it reaches the center of Earth
c. / speed up until it reaches the other side of Earth
d. / stop at the center of Earth

____42.Ocean tides occur mainly because _____.

a. / of the gravitational pull of the sun on Earth
b. / water normally runs to the side of Earth away from the sun
c. / of different gravitational pulls of the moon on opposite sides of Earth
d. / as Earth rotates it leaves the ocean water somewhat behind it
e. / none of the above

____43.The effect of the sun's pull on Earth's oceans is much less visible than that of the moon's pull because _____.

a. / Earth is spinning so fast
b. / the sun is so far away
c. / Earth is orbiting so fast
d. / the sun is radiating a lot of energy
e. / none of the above

____44.A lunar eclipse happens when _____.

a. / the moon is between Earth and the sun
b. / the sun is between Earth and the moon
c. / Earth is between the moon and the sun

____45.A solar eclipse happens when _____.

a. / the moon is between Earth and the sun
b. / Earth is between the moon and the sun
c. / the sun is between Earth and the moon

____46.Earth tides in which the solid surface of Earth rises and falls are caused by _____.

a. / many volcanic eruptions
b. / different forces between the moon and opposite parts of Earth
c. / the alignment of the sun and the moon
d. / the motion of water caused by ocean tides
e. / none of the above—the solid surface of Earth cannot have tides.

____47.Suppose the moon had twice its present mass and still orbited Earth at the same distance. In that case _____.

a. / the ocean tide facing the moon would rise, and the other tide would lower
b. / the ocean tides would be the same as they are now
c. / both ocean tides would be smaller
d. / the ocean tide facing the moon would lower, and the other tide would rise
e. / both ocean tides would be higher

____48.During an eclipse of the sun, when the moon comes between the sun and Earth, the ocean tide nearest the moon would be _____.

a. / extra low
b. / extra high
c. / both A and B
d. / the same as always

____49.There would still be two ocean tides per 24 hours if _____.

a. / the sun's influence on the tides were negligible
b. / Earth and moon had equal masses
c. / the moon had more mass than Earth
d. / any of the above
e. / none of the above

____50.There are two main processes going on in the sun that keep the sun in existence. These processes are gravitation and _____.

a. / nuclear fusion
b. / electrostatic repulsion
c. / heat absorption

____51.A black hole is an object that _____.

a. / alters the space around it
b. / has an enormous density
c. / has an enormous gravitational field near it
d. / has an escape speed greater than the speed of light
e. / all of the above

____52.If the sun were to collapse to form a black hole (quite unlikely), Earth would _____.

a. / immediately disappear
b. / spiral into the black hole
c. / orbit the black hole just as it orbits the sun now
d. / leave the solar system in the direction of its tangential velocity
e. / be drawn into the black hole

____53.When a star collapses to form a black hole, its mass _____.

a. / decreases
b. / remains the same
c. / increases

____54.In order for tidal forces to be significant, there must be a relatively large distance between _____.

a. / the body causing tides and the body experiencing tides
b. / opposite sides of the body experiencing tides
c. / both A and B
d. / none of the above

____55.Which produces a greater tidal effect in your body, the moon or a 1-kg melon that you hold above your head?

a. / Not enough information given to make a reasonable estimate
b. / The moon
c. / The melon

____56.Which of these three produces the greatest tidal effect on you right now?

a. / Earth
b. / The moon
c. / The sun

____57.A man who weighs 600 N at Earth's surface stands on top of a very tall ladder so he is one Earth radius above Earth's surface. How much does he weigh?

a. / zero
b. / 150 N
c. / 300 N
d. / 600 N
e. / none of the above

____58.If Earth had twice its present mass, but the same radius, what would be the value of g?

a. / 0 m/s2
b. / 4.9 m/s2
c. / 9.8 m/s2
d. / 19.6 m/s2
e. / 39.2 m/s2

____59.How many high tides are there normally each day on a typical ocean beach?

a. / 0
b. / 1
c. / 2
d. / 4

____60.If the radius of Earth were one half what it is now, and the mass were the same, what would be the value of g?

a. / 0 m/s2
b. / 4.9 m/s2
c. / 9.8 m/s2
d. / 19.6 m/s2
e. / 39.2 m/s2

____61.The reason satellites orbit Earth at least 150 km above the surface is to _____.

a. / be above Earth's gravity
b. / make sure they are higher than the highest mountains
c. / be above Earth's atmosphere
d. / keep them out of the way of commercial airliners.
e. / all of the above

____62.The speed of a satellite in a circular orbit is _____.

a. / constant
b. / not constant
c. / constantly increasing

____63.The speed of a satellite in an elliptical orbit is _____.

a. / independent of the height of the satellite
b. / not constant
c. / constant

____64.A period of a satellite is defined as _____.

a. / the time for a satellite to cross the United States
b. / 1 second
c. / the time for a satellite to make one complete revolution around Earth
d. / 90 seconds
e. / 24 hours

____65.The higher a satellite is, the _____.

a. / less its speed is
b. / greater its speed is
c. / longer its period is
d. / both A and C
e. / both B and C

____66.A circle is a special case of _____.

a. / a hyperbola
b. / a parabola
c. / an ellipse
d. / a focus

____67.The circular orbit of a satellite orbiting Earth is characterized by a constant _____.

a. / speed
b. / radius
c. / magnitude of acceleration
d. / all of the above
e. / none of the above

____68.The fastest moving planet in a solar system is _____.

a. / the most massive planet
b. / any planet (they all move at the same speed)
c. / the smallest planet
d. / the planet nearest the sun

____69.Pluto takes a longer time to travel around the sun than Earth takes because Pluto _____.

a. / has farther to go
b. / goes slower
c. / both A and B
d. / none of the above

____70.An object is placed exactly halfway between Earth and the moon. The object will fall toward _____.

a. / the moon
b. / Earth
c. / neither Earth nor the moon

____71.A projectile is fired vertically from the surface of Earth at 10 km/s. The projectile will _____.

a. / rise and then fall back to Earth's surface
b. / go into an elliptical orbit about Earth
c. / go into a circular orbit about Earth
d. / none of the above

____72.A vertically oriented rocket that maintains a continuous upward velocity of 8 km/s will _____.

a. / not to be able to escape Earth
b. / escape Earth

____73.An object dropped from rest almost infinitely far from Earth falls to Earth because of Earth's gravitational field, and strikes the surface with a speed of about _____.

a. / 8 km/s
b. / 9.8 m/s
c. / 11 km/s
d. / none of the above

____74.Compared to the period of a satellite in orbit close to Earth, the period of a satellite in orbit far from Earth is _____.

a. / the same
b. / longer
c. / shorter
d. / Not enough information

____75.The force of gravity does work on a satellite when it is in _____.

a. / circular orbit
b. / elliptical orbit
c. / both A and B
d. / neither A nor B

____76.Where does a satellite in an elliptical orbit have the greatest kinetic energy?

a. / At the point closest to the planet
b. / Exactly at the point halfway to the planet
c. / At the point farthest from the planet
d. / Anywhere -- its kinetic energy is constant
e. / More information is needed

____77.Where does a satellite in a circular orbit have the greatest kinetic energy?

a. / At the point farthest from the planet
b. / Exactly at the point halfway to the planet
c. / At the point closest to the planet
d. / Anywhere—its kinetic energy is constant
e. / More information is needed

____78.What remains constant for a satellite in an elliptical orbit?

a. / Its speed
b. / Its potential energy
c. / Its total energy
d. / Its kinetic energy
e. / Its distance from the planet

____79.The curvature of Earth is such that for every 8000 m tangent to the surface, the surface drops about _____.

a. / 0 m
b. / 2.5 m
c. / 5 m
d. / 10 m
e. / 20 m

____80.Minimal orbital speed about Earth is approximately 8 km/s. Minimal orbital speed about the moon would be _____.

a. / less than 8 km/s
b. / about 8 km/s
c. / more than 8 km/s

Problem

81.By what factor would your weight be multiplied if Earth's diameter were 2 times as big and Earth's mass remained unchanged?

82.What would a person who weighs 610 N on Earth weigh on a planet that has the same mass as Earth but half its radius?

83.Imagine you are standing atop a ladder so tall that you are 2 Earth radii from Earth's center. What is your weight at the top of the ladder, relative to your weight on the ground?

84.A woman whose mass is 70 kg on Earth's surface is in a spacecraft at a height of twice Earth's radius (that is, 3 Earth radii) above Earth's surface. What is her mass (not weight) there?

85.A man whose mass is 90 kg is in a spacecraft at a height equal to Earth's diameter (not radius!) above Earth's surface. What is the gravitational force between him and Earth at this distance?

86.Satellites often orbit 640 km above Earth's surface (640 km = 10% of Earth's radius). What is Earth's approximate gravitational field, g, in satellite territory?

87.What is Earth's gravitational field, g, 2 Earth-diameters from Earth's surface (5 r from Earth's center)?

88.Suppose you're standing on the surface of a shrinking planet. If it shrinks to its diameter (and its mass remains the same), how many times as much would you weigh on the shrunken surface?