Torque and Rotational Motion
Which of the following scenarios represents rotational equilibrium?
A spinning top slowing down.
A car accelerating around a curve.
A ceiling fan rotating at a constant speed.
A ball rolling down a hill.
A system has a net force of zero but a non-zero net torque. Which of the following is true?
It is in translational equilibrium but not rotational equilibrium.
It is in rotational equilibrium but not translational equilibrium.
It is in both translational and rotational equilibrium.
It is in neither translational nor rotational equilibrium.
A ladder leans against a wall. What conditions must be met for the ladder to be in both translational and rotational equilibrium?
The sum of the forces in the x and y direction must be zero.
The sum of the torques about any point must be zero.
Both the sum of the forces and the sum of the torques must be zero.
The sum of the forces must be constant.
A seesaw has two people of different weights sitting at different distances from the pivot. The seesaw is supported such that it is level (translational equilibrium). If the support is suddenly removed, what will happen?
The net torque will be zero and there will be no angular acceleration.
The net torque will be non-zero, causing angular acceleration.
The seesaw will remain in translational equilibrium.
The seesaw will move only translationally.
What happens to the angular velocity of an object if the net torque acting on it is zero?
It increases.
It decreases.
It remains constant.
It becomes zero.
Three forces act on a beam. Force 1 is 10N at 2m from the pivot, force 2 is 5N at 4m from the pivot in the opposite direction, and force 3 is 2N at the pivot. Is the beam in rotational equilibrium?
Yes, because the net torque is zero.
No, because the net torque is not zero.
Yes, because the net force is zero.
It cannot be determined without knowing the moment of inertia.
A wheel with a moment of inertia of 2 experiences a net torque of 5 Nm. What is its angular acceleration?
2.5
10
0.4
7

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A uniform beam of length L and weight W is supported by a pivot at one end and a cable at the other end. The cable makes an angle of with the beam. Determine the tension in the cable in terms of W and .
T = W / sin()
T = W / (2sin())
T = W * sin()
T = 2W / sin()
A rotating wheel has a kinetic energy of 100 J. If a torque of 10 Nm is applied to stop the wheel, through what angle does the wheel rotate before coming to rest?
5 radians
10 radians
15 radians
20 radians
A spinning disk collides with a stationary disk of the same size and mass. If the two disks stick together after the collision, what is their final angular velocity in terms of the initial angular velocity of the first disk?