AP Physics Circular Motion Exam Questions and Correct Answers Latest Update 2024 Already Passed
Multiple Correct: A person stands on a merry-go-round which is rotating at constant angular speed.
Which of the following are true about the frictional force exerted on the person by the merry-go-round?
Select two answers.
(A) The force is greater in magnitude than the frictional force exerted on the person by the merry-go-
round.
(B) The force is opposite in direction to the frictional force exerted on the merry-go-round by the
person.
(C) The force is directed away from the center of the merry-go-round.
(D) The force is dependent on the person's mass. - Answers B and D
A ball attached to a string is whirled around in a horizontal circle having a radius R. If the radius of the
circle is changed to 4R and the same centripetal force is applied by the string, the new speed of the ball
is which of the following?
(A) One-quarter the original speed
(B) One-half the original speed
(C) The same as the original speed
(D) Twice the original speed - Answers D, F = mv2/r; v=(square root)Fr/m ; all other variables being
constant, if r is quadrupled, is doubled
A racing car is moving around the circular track of radius 300 meters shown above. At the instant when
the car's velocity is directed due east, its acceleration is directed due south and has a magnitude of 3
meters per second squared. When viewed from above, the car is moving
(A) clockwise at 30 m/s
(B) clockwise at 10 m/s
(C) counterclockwise at 30 m/s
(D) counterclockwise at 10 m/s - Answers A, a = v2/r
The horizontal turntable shown above rotates at a constant rate. As viewed from above, a coin on the
turntable moves counterclockwise in a circle as shown. Which of the following vectors best represents
the direction of the frictional force exerted on the coin by the turntable when the coin is in the position
shown?
(A) Straight Right
, (B) Diagonal Left
(C) Straight Down
(D) Straight Up - Answers C, The frictional force acts as the centripetal force (toward the center)
In which of the following situations would an object be accelerated? Select two answers.
(A) It moves in a straight line at constant speed.
(B) It moves with uniform circular motion
C) It travels as a projectile in a gravitational field with negligible air resistance.
(D) It is at rest. - Answers B and C, Acceleration occurs when an object is changing speed and/or
direction
An automobile moves at constant speed down one hill and up another hill along the smoothly curved
surface shown above. Which of the following diagrams best represents the directions of the velocity and
the acceleration of the automobile at the instant that it is at the lowest position. as shown?
a) Velocity straight right, Acceleration straight down
b) Velocity straight right, acceleration straight up
c) Velocity straight right, Acceleration straight right
d) Velocity straight right, Acceleration straight left - Answers B, Velocity is tangential, acceleration points
toward the center of the circular path
A car initially travels north and then turns to the left along a circular curve. This causes a package on the
seat of the car to slide toward the right side of the car. Which of the following is true of the net force on
the package while it is sliding?
(A) The force is directed away from the center of the circle.
(B) There is not enough force directed north to keep the package from sliding.
(C) There is not enough force tangential to the car's path to keep the package from sliding.
(D) There is not enough force directed toward the center of the circle to keep the package from sliding. -
Answers D, To move in a circle, a force directed toward the center of the circle is required. While the
package slides to the right in the car, it is actually moving in its original straight line path while the car
turns from under it.
A child has a toy tied to the end of a string and whirls the toy at constant speed in a horizontal circular
path of radius R. The toy completes each revolution of its motion in a time period T. What is the
magnitude of the acceleration of the toy?
Multiple Correct: A person stands on a merry-go-round which is rotating at constant angular speed.
Which of the following are true about the frictional force exerted on the person by the merry-go-round?
Select two answers.
(A) The force is greater in magnitude than the frictional force exerted on the person by the merry-go-
round.
(B) The force is opposite in direction to the frictional force exerted on the merry-go-round by the
person.
(C) The force is directed away from the center of the merry-go-round.
(D) The force is dependent on the person's mass. - Answers B and D
A ball attached to a string is whirled around in a horizontal circle having a radius R. If the radius of the
circle is changed to 4R and the same centripetal force is applied by the string, the new speed of the ball
is which of the following?
(A) One-quarter the original speed
(B) One-half the original speed
(C) The same as the original speed
(D) Twice the original speed - Answers D, F = mv2/r; v=(square root)Fr/m ; all other variables being
constant, if r is quadrupled, is doubled
A racing car is moving around the circular track of radius 300 meters shown above. At the instant when
the car's velocity is directed due east, its acceleration is directed due south and has a magnitude of 3
meters per second squared. When viewed from above, the car is moving
(A) clockwise at 30 m/s
(B) clockwise at 10 m/s
(C) counterclockwise at 30 m/s
(D) counterclockwise at 10 m/s - Answers A, a = v2/r
The horizontal turntable shown above rotates at a constant rate. As viewed from above, a coin on the
turntable moves counterclockwise in a circle as shown. Which of the following vectors best represents
the direction of the frictional force exerted on the coin by the turntable when the coin is in the position
shown?
(A) Straight Right
, (B) Diagonal Left
(C) Straight Down
(D) Straight Up - Answers C, The frictional force acts as the centripetal force (toward the center)
In which of the following situations would an object be accelerated? Select two answers.
(A) It moves in a straight line at constant speed.
(B) It moves with uniform circular motion
C) It travels as a projectile in a gravitational field with negligible air resistance.
(D) It is at rest. - Answers B and C, Acceleration occurs when an object is changing speed and/or
direction
An automobile moves at constant speed down one hill and up another hill along the smoothly curved
surface shown above. Which of the following diagrams best represents the directions of the velocity and
the acceleration of the automobile at the instant that it is at the lowest position. as shown?
a) Velocity straight right, Acceleration straight down
b) Velocity straight right, acceleration straight up
c) Velocity straight right, Acceleration straight right
d) Velocity straight right, Acceleration straight left - Answers B, Velocity is tangential, acceleration points
toward the center of the circular path
A car initially travels north and then turns to the left along a circular curve. This causes a package on the
seat of the car to slide toward the right side of the car. Which of the following is true of the net force on
the package while it is sliding?
(A) The force is directed away from the center of the circle.
(B) There is not enough force directed north to keep the package from sliding.
(C) There is not enough force tangential to the car's path to keep the package from sliding.
(D) There is not enough force directed toward the center of the circle to keep the package from sliding. -
Answers D, To move in a circle, a force directed toward the center of the circle is required. While the
package slides to the right in the car, it is actually moving in its original straight line path while the car
turns from under it.
A child has a toy tied to the end of a string and whirls the toy at constant speed in a horizontal circular
path of radius R. The toy completes each revolution of its motion in a time period T. What is the
magnitude of the acceleration of the toy?
