Question 1

An astronaut lands on a previously unknown planet of radius 2350. km and she measures the acceleration of gravity to be 3.20 m/s2.
(a) What is the mass of this new planet?
(b) What does the astronaut weigh on this new planet if she weighs 384. N on Earth?

Accepted Answer

(a) 0.26 ×...

Question 2

Imagine yourself in a car traveling around a sharp curve. The "centripetal" force is inward, yet why do you slide outward and not inward?

Accepted Answer

In the absence of an inward force, you w...

Question 3

Consider a 2.4 kilogram feather (Big Bird) on the planet Mars. [Earth mass = 6.0 × 1024 kg = 9.3 × Mars mass; Earth radius = 6380. km = 1.89 × Mars radius]
(a) What does the feather weigh on Mars? 
(b) What would the same feather weigh on Earth?

Accepted Answer

9.1 N on M...

Question 4

A pilot makes an outside vertical loop of radius 320 m. At the top of his loop he is pushing down on his seat with only one-half of his normal weight. How fast is he moving?

Accepted Answer

The answer of A pilot makes an outside vertical loop...

Question 5

Fred swings around a 0.40 kg ball attached to a string at constant speed in an almost horizontal circle of radius 1.3 meters. If one revolution takes 1.4 s:
(a) What is the angular speed of the ball?
(b) What centripetal force is exerted on the ball?

Accepted Answer

(a) 4.5 ra...

Question 6

A bicycle wheel has an outside diameter of 66 cm. How far does a point on the rim travel when the wheel rotates through an angle of 70°?

Accepted Answer

The answer of A bicycle wheel has an outside diameter...

Question 7

A roller coaster car (mass = M)  is on a track that forms a circular loop (radius = r)  in the vertical plane. If the car is to just maintain contact with the track at the top of the loop, what is the minimum value for its speed at that point?

Accepted Answer

A)   2 Mrg
B)  
C)   / 
D)   Mrg
E)  F) A) and B)
G) None of the above

Question 8

James is twirling a rock around a horizontal circle on the end of a string. Figure 7-2 is a top view (motion is counterclockwise)  Figure 7-2
 
If the speed is constant what is the acceleration at point A?

Accepted Answer

A)   zero
B)   centrifugal
C)   r
D)   v / r
E)   centripetalF) A) and B)
G) A) and C)

Question 9

A race car, traveling at a constant speed of 50 m/s, drives around a circular track of radius 250 m. What angular acceleration does it experience?

Accepted Answer

A)   1.0 × 101 rad/s2
B)   zero
C)   1.0 × 104 rad/s2
D)   6.3 × 102 rad/s2
E)   2.0 × 103 rad/s2F) B) and E)
G) A) and E)

Question 10

The speed of Halley's comet, while traveling in its elliptical orbit around the sun,

Accepted Answer

A)   increases as it nears the sun.
B)   is constant.
C)   is zero at two points in the orbit.
D)   is zero at four points in the orbit.
E)   decreases as it nears the sun.F) A) and D)
G) A) and C)

Question 11

Newton never knew the numerical value of "his" universal gravitational constant G.

Accepted Answer

A) True 
 B)False

Question 12

Who was the first person to realize that the planets move in elliptical paths around the sun?

Accepted Answer

A)   Galileo
B)   Copernicus
C)   Kepler
D)   Einstein
E)   BraheF) None of the above
G) All of the above

Question 13

What is the gravitational force on a 70. kg person on the Earth, due to the moon? The mass of the moon is 7.36 x 1022 kg and the distance to the moon is 3.82 × 108 m.

Accepted Answer

Question 14

What is the centripetal acceleration of a point on the perimeter of a bicycle wheel of diameter 70. cm when the bike is moving 8.0 m/s?

Accepted Answer

A)   91 m/s2
B)   1.8 × 102 m/s2
C)   2.1 × 10-2 m/s2
D)   66 m/s2
E)   2.7 × 102 m/s2F) A) and E)
G) B) and D)

Question 15

As you know, the Earth has an orbital period of one year at an orbital radius of one AU. If a new "minor planet" were to be found in a circular orbit with radius 13. AU, what would be its period?

Accepted Answer

Remembering Kepler's...

Question 16

A fan blade, whose diameter is 1.0 m, is turning with an angular velocity of 2.0 rad/s. What is the tangential velocity of a point on the tip of the blade?

Accepted Answer

A)   1.5 m/s
B)   2.0 m/s
C)   5.0 cm/s
D)   0.50 m/s
E)   1.0 m/sF) B) and E)
G) A) and D)

Question 17

To test his gravitational theory, Newton calculated the period of the moon around the Earth to see if he got the observed 27.3 days. Section 7.6 derived T = 2π  . How could Newton calculate T when he didn't know the value of G or of M?

Accepted Answer

g = GM/R² so T = 2π
...

Question 18

A flywheel, of radius 1 m, is spinning with a constant angular velocity of 2 rad/s. What is the centripetal acceleration of a point on the wheel's rim?

Accepted Answer

A)   2 m/s2
B)   8 m/s2
C)   4 m/s2
D)   6 m/s2
E)   1 m/s2F) B) and E)
G) All of the above

Question 19

A spherically symmetric planet has four times the Earth's mass and twice its radius. If a jar of peanut butter weighs 12. N on the surface of the Earth, how much would it weigh on the surface of this planet?

Accepted Answer

A)   30 N
B)   24 N
C)   12 N
D)   6 N
E)   18 NF) B) and E)
G) None of the above

Question 20

A girl attaches a rock to a string, which she then swings counter-clockwise in a horizontal circle. The string breaks at point P in Figure 7-4, which shows a bird's-eye view (i.e., as seen from above) Figure 7-4
  
Which path (A-E) will the rock follow?

Accepted Answer

The answer of A girl attaches a rock to a...

Exam 7: Circular Motion and Gravitation

Imagine yourself in a car traveling around a sharp curve. The "centripetal" force is inward, yet why do you slide outward and not inward?

Correct AnswerverifiedIn the absence of an inward force, you w...View AnswerShow Answer

James is twirling a rock around a horizontal circle on the end of a string. Figure 7-2 is a top view (motion is counterclockwise) Figure 7-2 If the speed is constant what is the acceleration at point A?

Correct AnswerverifiedShow Answer

What is the centripetal acceleration of a point on the perimeter of a bicycle wheel of diameter 70. cm when the bike is moving 8.0 m/s?

Correct AnswerverifiedShow Answer

A flywheel, of radius 1 m, is spinning with a constant angular velocity of 2 rad/s. What is the centripetal acceleration of a point on the wheel's rim?

Correct AnswerverifiedShow Answer

A bicycle wheel has an outside diameter of 66 cm. How far does a point on the rim travel when the wheel rotates through an angle of 70°?

Correct AnswerverifiedShow Answer

The speed of Halley's comet, while traveling in its elliptical orbit around the sun,

Correct AnswerverifiedShow Answer

Who was the first person to realize that the planets move in elliptical paths around the sun?

Correct AnswerverifiedShow Answer

Fred swings around a 0.40 kg ball attached to a string at constant speed in an almost horizontal circle of radius 1.3 meters. If one revolution takes 1.4 s: (a) What is the angular speed of the ball? (b) What centripetal force is exerted on the ball?

Correct Answerverified(a) 4.5 ra...View AnswerShow Answer

A girl attaches a rock to a string, which she then swings counter-clockwise in a horizontal circle. The string breaks at point P in Figure 7-4, which shows a bird's-eye view (i.e., as seen from above) Figure 7-4 Which path (A-E) will the rock follow?

Correct AnswerverifiedShow Answer

As you know, the Earth has an orbital period of one year at an orbital radius of one AU. If a new "minor planet" were to be found in a circular orbit with radius 13. AU, what would be its period?

Correct AnswerverifiedRemembering Kepler's...View AnswerShow Answer

A spherically symmetric planet has four times the Earth's mass and twice its radius. If a jar of peanut butter weighs 12. N on the surface of the Earth, how much would it weigh on the surface of this planet?

Correct AnswerverifiedShow Answer

A pilot makes an outside vertical loop of radius 320 m. At the top of his loop he is pushing down on his seat with only one-half of his normal weight. How fast is he moving?

Correct AnswerverifiedShow Answer

To test his gravitational theory, Newton calculated the period of the moon around the Earth to see if he got the observed 27.3 days. Section 7.6 derived T = 2π . How could Newton calculate T when he didn't know the value of G or of M?

Correct Answerverifiedg = GM/R2 so T = 2π ...View AnswerShow Answer

Consider a 2.4 kilogram feather (Big Bird) on the planet Mars. [Earth mass = 6.0 × 1024 kg = 9.3 × Mars mass; Earth radius = 6380. km = 1.89 × Mars radius] (a) What does the feather weigh on Mars? (b) What would the same feather weigh on Earth?

Correct Answerverified9.1 N on M...View AnswerShow Answer

A fan blade, whose diameter is 1.0 m, is turning with an angular velocity of 2.0 rad/s. What is the tangential velocity of a point on the tip of the blade?

Correct AnswerverifiedShow Answer

An astronaut lands on a previously unknown planet of radius 2350. km and she measures the acceleration of gravity to be 3.20 m/s2. (a) What is the mass of this new planet? (b) What does the astronaut weigh on this new planet if she weighs 384. N on Earth?

Correct Answerverified(a) 0.26 ×...View AnswerShow Answer

A race car, traveling at a constant speed of 50 m/s, drives around a circular track of radius 250 m. What angular acceleration does it experience?

Correct AnswerverifiedShow Answer

A roller coaster car (mass = M) is on a track that forms a circular loop (radius = r) in the vertical plane. If the car is to just maintain contact with the track at the top of the loop, what is the minimum value for its speed at that point?

Correct AnswerverifiedShow Answer

Newton never knew the numerical value of "his" universal gravitational constant G.

Correct AnswerverifiedShow Answer

What is the gravitational force on a 70. kg person on the Earth, due to the moon? The mass of the moon is 7.36 x 1022 kg and the distance to the moon is 3.82 × 108 m.

Correct AnswerverifiedShow Answer

Correct Answer
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In the absence of an inward force, you w...
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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(a) 4.5 ra...
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Correct Answer
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Correct Answer
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Remembering Kepler's...
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Correct Answer
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Correct Answer
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Correct Answer
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g = GM/R² so T = 2π
...
View Answer

Consider a 2.4 kilogram feather (Big Bird) on the planet Mars. [Earth mass = 6.0 × 10²⁴ kg = 9.3 × Mars mass; Earth radius = 6380. km = 1.89 × Mars radius] (a) What does the feather weigh on Mars? (b) What would the same feather weigh on Earth?

Correct Answer
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9.1 N on M...
View Answer

Correct Answer
verified

An astronaut lands on a previously unknown planet of radius 2350. km and she measures the acceleration of gravity to be 3.20 m/s². (a) What is the mass of this new planet? (b) What does the astronaut weigh on this new planet if she weighs 384. N on Earth?

Correct Answer
verified
(a) 0.26 ×...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
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What is the gravitational force on a 70. kg person on the Earth, due to the moon? The mass of the moon is 7.36 x 10²² kg and the distance to the moon is 3.82 × 10⁸ m.

Correct Answer
verified