Uniform Circular Motion Practice Multiple Choice Test

 

1.

A racecar is traveling in uniform circular motion around a racetrack. What happens to the centripetal acceleration of the car if the speed is doubled but the radius of the circle remains constant?

A)

It remains the same.

B)

It increases by a factor of 2.

C)

It increases by a factor of 4.

D)

It is decreased by a factor of one-half.

E)

It is decreased by a factor of one-fourth.

 

A small car of mass M travels along a straight, horizontal track. As suggested in the figure, the track then bends into a vertical circle of radius R.

2.

What is the minimum acceleration that the car must have at the top of the track if it is to remain in contact with the track?

A)

4.91 m/s2, downward

B)

4.91 m/s2, upward

C)

9.81 m/s2, upward

D)

9.81 m/s2, downward

E)

19.6 m/s2, upward

 

3.

A boy is whirling a stone around his head by means of a string. The string makes one complete revolution every second, and the tension in the string,FT, is directed horizontally. The boy then speeds up the stone, keeping the radius of the circle constant, so that the string makes two complete revolutions every second. What happens to the tension in the sting?

A)

The tension is unchanged.

B)

The tension reduces to half of its original value.

C)

The tension increases to twice its original value.

D)

The tension increases to four times its original value.

E)

The tension reduces to one-fourth of its original value.

 

4.

A certain string just breaks when it is under 400 N of tension. A boy uses this string to whirl a 10-kg stone in a horizontal circle of radius 10 m. The boy continuously increases the speed of the stone. At approximately what speed will the string break? Assume the tension force is directed horizontally.

A)

10 m/s

B)

20 m/s

C)

80 m/s

D)

100 m/s

E)

400 m/s

 

5.

Which force is responsible for holding a car in an unbanked curve?

A)

the car's weight

B)

the force of friction

C)

the reaction force to the car's weight

D)

the vertical component of the normal force

E)

the horizontal component of the normal force

 

 

6.

A satellite is placed in equatorial orbit above Mars, which has a radius of 3397 km and a mass MM = 6.40  1023 kg. The mission of the satellite is to observe the Martian climate from an altitude of 488 km. What is the orbital period of the satellite?

A)

9.18  102 s

B)

3.62  103 s

C)

7.36  103 s

D)

1.08  105 s

E)

7.27  1012 s

7.

Determine the minimum angle at which a roadbed should be banked so that a car traveling at 20.0 m/s can safely negotiate the curve without the aid of friction. The radius of the curve is 2.00 x 102 m.

A)

0.200

B)

0.581

C)

11.5

D)

19.6

E)

78.2

 

8.

A 0.25-kg ball attached to a string is rotating in a horizontal circle of radius 0.5 m. Assume the tension force is directed horizontally. If the ball revolves twice every second, what is the tension in the string?

A)

2 N

B)

5 N

C)

7 N

D)

10 N

E)

20 N

 

 

9.

Consider a hypothetical planet in our solar system whose average distance from the Sun is about four times that of Earth. Determine the orbital period for this hypothetical planet.

A)

0.25 year

B)

2.5 years

C)

4 years

D)

8 years

E)

16 years

 

 

10.

A plane is traveling at 200 m/s following the arc of a vertical circle of radius R. At the top of its path, the passengers experience "weightlessness." To one significant figure, what is the value of R?

A)

200 m

B)

1000 m

C)

2000 m

D)

4000 m

E)

40 000 m

 

 


Answer Key

 

1.

C

2.

D

3.

D

4.

B

5.

B

6.

C

7.

C

8.

E

9.

D

10.

D