Question 1

A car travels around a curve with constant speed. The correct statement from the following is

Accepted Answer

A)   the car has an acceleration directed inward toward the center of the curve.
B)   the velocity of the car is constant.
C)   the car has an acceleration directed outward from the center of the curve.
D)   the car has zero acceleration.
E)   the car has an acceleration directed in the instantaneous direction of the velocity vector.

Question 2

Earth's gravity attracts a person with a force of 120 lbs. The force with which the Earth is attracted towards the person is

Accepted Answer

A)   billions and billions of tons.
B)   120 lbs.
C)   small but not zero.
D)   zero.

Question 3

A car can move at constant speed on a level curve on a highway as long as the force of ___________ between the pavement and tires is sufficient to provide the necessary centripetal force.

Accepted Answer

The answer of A car can move at constant speed...

Question 4

Strictly speaking, Newton's law of universal gravitation, F = Gm1m2/r2, is valid only if the masses are either point masses or __________________.

Accepted Answer

perfect (uniform) sp...

Question 5

A rock that weighs 100 lb on Earth is taken to the Moon. Which of the following statements accurately describes what would be observed?

Accepted Answer

A)   The rock is easier to lift because its mass is less on the moon.
B)   The rock is easier to lift because its weight is less on the moon.
C)   The rock is more difficult to lift because the Moon's radius is less than Earth's.
D)   The rock is just as difficult to lift on the Moon as it is on Earth because its mass hasn't changed.

Question 6

The mass of an apple on the Earth is 0.2 kg. On the Moon, the mass of the same apple would be

Accepted Answer

A)   greater than 0.2 kg.
B)   0.2 kg.
C)   greater than zero but less than 0.2 kg.
D)   zero.

Question 7

An object weighs 30 newtons on Earth. What is its approximate mass?

Accepted Answer

A)   640 kg
B)   30 g
C)   12 kg
D)   3 kg
E)   294 kg

Question 8

The orbit of Comet UX209 about the Sun is not a circle but it orbits once every 365 days, just as Earth does. UX209 is closer to the Sun in April than it is in October. Thus, the speed of UX209 as it moves along its orbit is

Accepted Answer

A)   steadily increasing all year long.
B)   greater in April than in October.
C)   greater in October than it is in April.
D)   steadily decreasing all year long.
E)   the same all year long.

Question 9

You spin your little brother on a "helicopter" ride, which means you hold hands and spin around a vertical axis, usually resulting in the little brother's feet lifting off the ground. During the "ride", the acceleration of your brother is

Accepted Answer

A)   inward toward you, and you must pull him inward.
B)   inward toward you, but you push him outward.
C)   tangential to the circular path, and that is why it takes two hands to give helicopter rides.
D)   outward from you, but he pushes you inward.
E)   outward from you because circular paths always have centrifugal acceleration.

Question 10

An object undergoes uniform circular motion. Which pair of vectors is perpendicular?

Accepted Answer

A)   Its centripetal acceleration and the centripetal force
B)   Its centripetal acceleration and velocity vectors
C)   All three vectors are mutually perpendicular: centripetal acceleration, centripetal force, and velocity.

Question 11

If two bicyclists move around a circular track of radius 100 m, at the same speed, 10 m/s, but in opposite directions, then

Accepted Answer

A)   one has centripetal acceleration of 1 m/s2 and the other has centrifugal acceleration of 1 m/s2.
B)   they have opposite accelerations, +1 m/s2 (inward)  and -1 m/s2 (outward) .
C)   they have equal size accelerations, 1 m/s2.
D)   they might have different accelerations, depending on whether they have identical mass or not.

Question 12

If a ball at the end of a string is whirled in a vertical circle at constant speed, the tension will be

Accepted Answer

A)   the same throughout the motion.
B)   greatest at the highest point in the motion.
C)   greatest at the lowest point in the motion.
D)   greatest at a point where the string is instantaneously parallel to the ground.

Question 13

Two cyclists of different mass take a turn on a level road. They follow the same path and are moving the same constant speed for the turn. Which of the following statements is correct?

Accepted Answer

A)   The acceleration is zero for both.
B)   The acceleration is larger for the less massive cyclist.
C)   The acceleration is larger for the more massive cyclist.
D)   The acceleration is not zero but is the same for both.

Question 14

A ball is whirled on the end of a string in a horizontal circle at constant speed. Suddenly, the string breaks. Immediately after the string breaks, the ball will

Accepted Answer

A)   have a horizontal velocity away from the center of the circle.
B)   have a horizontal velocity that is tangential to the circle.
C)   have a horizontal velocity toward the center of the circle.
D)   have a horizontal velocity partly in away from the center of the circle and partly tangent to the circle.
E)   have no horizontal velocity.

Question 15

A person weighing 500 N rides on a Ferris wheel sitting on a bathroom scale. At the highest point of motion, the scale reads 200 N while the person continues to move in a circular path. The centripetal force on the person at this point is ___________ N.

Accepted Answer

The answer of A person weighing 500 N rides on...

Question 16

In Vienna, there is a Ferris wheel designed so that the passengers ride in a standing position. If one of the passengers were standing on a bathroom scale while the ride rotated at a constant speed, the scale would read lowest at

Accepted Answer

A)   the lowest point in the ride.
B)   the highest point in the ride.
C)   the point in the ride where they were ascending most rapidly.
D)   the point in the ride where they were descending most rapidly.

Question 17

During a new Moon, when the Sun and the Moon are on the same side of the Earth, the people who live next to the ocean will see about how many high tides per day?

Accepted Answer

A)   One
B)   Two
C)   Three
D)   Four

Question 18

A cyclist races around a circular track at the constant speed of 20 m/s. The radius of the track is 40 m. The dentripetal acceleration of the cyclist is

Accepted Answer

A)   zero.
B)   10 m/s2, toward the center of the track.
C)   10 m/s2, downward.
D)   20 m/s2, in the direction of travel.

Question 19

Arnold can bench press 315 pounds in his gym in California. That is exactly six big 45-pound weight plates and the 45-pound bar. He can lift all that one time, but he cannot lift 325 pounds even once. At the NASA gym on the Moon, Arnold would

Accepted Answer

A)   be able to bench press more than 315 pounds.
B)   be able to bench press the bar and more than 6 weight plates.
C)   be unable to bench press 315 pounds due to weak gravitational field of the Moon.

Question 20

In order to move in a perfectly circular path, the net force on an object must

Accepted Answer

A)   always change magnitude but not direction.
B)   always change direction but not magnitude.
C)   always change both magnitude and direction.
D)   have a constant magnitude and direction.
E)   equal zero.

Exam 5: Circular Motion, the Planets, and Gravity

You spin your little brother on a "helicopter" ride, which means you hold hands and spin around a vertical axis, usually resulting in the little brother's feet lifting off the ground. During the "ride", the acceleration of your brother is

Correct AnswerverifiedShow Answer

If a ball at the end of a string is whirled in a vertical circle at constant speed, the tension will be

Correct AnswerverifiedShow Answer

The orbit of Comet UX209 about the Sun is not a circle but it orbits once every 365 days, just as Earth does. UX209 is closer to the Sun in April than it is in October. Thus, the speed of UX209 as it moves along its orbit is

Correct AnswerverifiedShow Answer

In order to move in a perfectly circular path, the net force on an object must

Correct AnswerverifiedShow Answer

During a new Moon, when the Sun and the Moon are on the same side of the Earth, the people who live next to the ocean will see about how many high tides per day?

Correct AnswerverifiedShow Answer

Strictly speaking, Newton's law of universal gravitation, F = Gm1m2/r2, is valid only if the masses are either point masses or __________________.

Correct Answerverifiedperfect (uniform) sp...View AnswerShow Answer

Earth's gravity attracts a person with a force of 120 lbs. The force with which the Earth is attracted towards the person is

Correct AnswerverifiedShow Answer

A ball is whirled on the end of a string in a horizontal circle at constant speed. Suddenly, the string breaks. Immediately after the string breaks, the ball will

Correct AnswerverifiedShow Answer

In Vienna, there is a Ferris wheel designed so that the passengers ride in a standing position. If one of the passengers were standing on a bathroom scale while the ride rotated at a constant speed, the scale would read lowest at

Correct AnswerverifiedShow Answer

A rock that weighs 100 lb on Earth is taken to the Moon. Which of the following statements accurately describes what would be observed?

Correct AnswerverifiedShow Answer

Two cyclists of different mass take a turn on a level road. They follow the same path and are moving the same constant speed for the turn. Which of the following statements is correct?

Correct AnswerverifiedShow Answer

The mass of an apple on the Earth is 0.2 kg. On the Moon, the mass of the same apple would be

Correct AnswerverifiedShow Answer

An object undergoes uniform circular motion. Which pair of vectors is perpendicular?

Correct AnswerverifiedShow Answer

A cyclist races around a circular track at the constant speed of 20 m/s. The radius of the track is 40 m. The dentripetal acceleration of the cyclist is

Correct AnswerverifiedShow Answer

A car travels around a curve with constant speed. The correct statement from the following is

Correct AnswerverifiedShow Answer

Arnold can bench press 315 pounds in his gym in California. That is exactly six big 45-pound weight plates and the 45-pound bar. He can lift all that one time, but he cannot lift 325 pounds even once. At the NASA gym on the Moon, Arnold would

Correct AnswerverifiedShow Answer

If two bicyclists move around a circular track of radius 100 m, at the same speed, 10 m/s, but in opposite directions, then

Correct AnswerverifiedShow Answer

A person weighing 500 N rides on a Ferris wheel sitting on a bathroom scale. At the highest point of motion, the scale reads 200 N while the person continues to move in a circular path. The centripetal force on the person at this point is ___________ N.

Correct AnswerverifiedShow Answer

A car can move at constant speed on a level curve on a highway as long as the force of ___________ between the pavement and tires is sufficient to provide the necessary centripetal force.

Correct AnswerverifiedShow Answer

An object weighs 30 newtons on Earth. What is its approximate mass?

Correct AnswerverifiedShow Answer

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Strictly speaking, Newton's law of universal gravitation, F = Gm₁m₂/r², is valid only if the masses are either point masses or __________________.

Correct Answer
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perfect (uniform) sp...
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