All AP Physics 1 Resources
Example Questions
Example Question #71 : Circular And Rotational Motion
A block of mass is attached to the end of a string. Determine the minimum angular velocity needed to keep the string taught while the block is swung in vertical circles.
None of these
At the top of the swing, both gravity and the tension of the string will be in the same direction, thus, this is where tension would be at a minimum.
At the very limit of being taught,
Thus,
Solving for
This will be the linear velocity.
The angular velocity will be
Combining equations
Plugging in values
Example Question #1071 : Ap Physics 1
A block of mass is attached to the end of a string. Determine the minimum angular velocity needed to keep the string taught while the block is swung in vertical circles.
None of these
At the top of the swing, both gravity and the tension of the string will be in the same direction, thus, this is where tension would be at a minimum.
At the very limit of being taught,
Thus,
Solving for
This will be the linear velocity.
The angular velocity will be
Combining equations
Plugging in values
Example Question #41 : Centripetal Force And Acceleration
Troy spins a ball attached to a string around in a vertical circle. Assume the ball travels at constant speed during its circular path. Which of the following is not constant throughout the ball's path?
Force of gravity on the ball
All of these are constant
Tension in the string
The rate at which the string does work on the ball
Angular momentum of the ball
Tension in the string
Let's go through each answer choice one by one. The force of gravity on the ball is always its mass times gravity, which is constant. The string's pull on the ball is always perpendicular to the ball's motion, so it isn't doing any work, and thus has a constant rate of work . The ball's angular momentum is always constant since its mass, the radius of the circle it's traveling in, and its speed are constant. The only the changing is the tension in the string. This is true because the ball needs the same center pulling force (centripetal force) throughout its path, but this centripetal force is constantly changing direction. For example, at the top of its path, the centripetal force must be down because that's the direction of the center of its circle of motion, but at the bottom, the centripetal force must be up. There are two forces on the ball, gravity and tension. The force of gravity is always down and constant, so the tension needs to change in order to keep the center pulling force the same. For example, when the ball is at the bottom of the circle, the force of gravity is away from the center of the circle, so tension must be higher to keep the center pull constant.
Example Question #42 : Centripetal Force And Acceleration
An airplane is traveling at and performs a vertical loop in . Determine the net force on the pilot at the bottom of the loop.
None of these
Circumference of a circle:
Distance plane travels during loop (which will be the circumference)
Centripetal acceleration:
Plugging in values:
Example Question #41 : Centripetal Force And Acceleration
An airplane is traveling at and performs a vertical loop in . Determine the force due to the seat on the pilot at the bottom of the loop
None of these
Circumference of a circle:
Distance plane travels during loop (which will be the circumference)
Centripetal acceleration:
Plugging in values:
Example Question #42 : Centripetal Force And Acceleration
An airplane is traveling at and performs a vertical loop in . Determine the radius of the loop.
Circumference of a circle:
Distance plane travels during loop (which will be the circumference)
Example Question #41 : Centripetal Force And Acceleration
A model train completes a circle of radius in . Determine the centripetal acceleration.
None of these
One circle is equal to , thus the linear velocity is:
Using
Example Question #41 : Centripetal Force And Acceleration
A model train completes a circle of radius in . Determine the centripetal force.
None of these
One circle is equal to , thus the linear velocity is
Using
Use Newton's second law:
Example Question #41 : Centripetal Force And Acceleration
A model train completes a circle of radius in . Determine the angular momentum.
None of these
One circle is equal to , thus the linear velocity is:
The definition of angular momentum:
Plugging in values:
Example Question #131 : Circular, Rotational, And Harmonic Motion
An object has a mass M, velocity V, and moves in a circle with radius R.
What happens to the centripetal acceleration on the object when the mass is doubled?
The centripetal acceleration remains the same.
The centripetal acceleration remains the same.
The centripetal acceleration is halved.
The centripetal acceleration is doubled.
The centripetal acceleration is quadrupled.
The centripetal acceleration remains the same.
The equation for centripetal acceleration is:
Where is the centripetal acceleration on an object, is the velocity of an object, and is the radius in which the object moves in a circle.
We can see that mass does not play a role in the centripetal acceleration of an object, so no matter what happens to the mass, the centripetal acceleration remains the same.
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