Exam 10: Rotation

A disk starts from rest and rotates about a fixed axis, subject to a constant net torque.The work done by the torque during the second revolution is ______ as the work done during the first revolution.

A uniform solid cylinder made of lead has the same mass and the same length as a uniform solid cylinder made of wood.The rotational inertia of the lead cylinder compared to the wooden one is:

A wheel starts from rest and has an angular acceleration of 4.0 rad/s².When it has made 10 rev its angular velocity is:

A disk with a rotational inertia of 5.0 kg.m² and a radius of 0.25 m rotates on a frictionless fixed axis perpendicular to the disk and through its center.A force of 8.0 N is applied along the rotation axis.The angular acceleration of the disk is:

One revolution per minute is about:

A flywheel rotating at 12 rev/s is brought to rest in 6 s.The magnitude of the average angular acceleration of the wheel during this process is:

This graph shows the angular velocity of a turntable as a function of time.What is its angular acceleration at t = 3.5 s?

For a wheel spinning on an axis through its center, the ratio of the radial acceleration of a point on the rim to the radial acceleration of a point halfway between the center and the rim is:

A torque of 470 N∙m acts on a flywheel.At the instant that the flywheel's angular speed is 56 rad/s, at what rate is work being done by the torque?

The angular velocity of a rotating wheel increases 2 rev/s every minute.The angular acceleration of this wheel is:

Four identical particles, each with mass m, are arranged in the x, y plane as shown.They are connected by light sticks to form a rigid body.If m = 2.0 kg and a = 1.0 m, the rotational inertia of this array about the y-axis is:

A 16 kg block is attached to a cord that is wrapped around the rim of a flywheel of diameter 0.40 m and hangs vertically, as shown.The rotational inertia of the flywheel is 0.50 kg∙m².When the block is released and the cord unwinds, the acceleration of the block is:

A disk is free to rotate on a fixed axis.A force of given magnitude F, in the plane of the disk, is to be applied.Of the following alternatives the greatest angular acceleration is obtained if the force is:

A wheel starts from rest and has an angular acceleration of 4.0 rad/s².The time it takes to make 10 revolutions is:

A rod is pivoted about its center.A 5-N force is applied 4 m from the pivot and another 5-N force is applied 2 m from the pivot, as shown.The magnitude of the total torque about the pivot is:

The angular speed of the minute hand of a watch is:

A and B are two solid cylinders made of aluminum.Their dimensions are shown.The ratio of the rotational inertia of B to that of A about the common axis X─X' is:

A small disk of radius R₁ is mounted coaxially with a larger disk of radius R₂.The disks are securely fastened to each other and the combination is free to rotate on a fixed axle that is perpendicular to a horizontal frictionless table top, as shown in the overhead view below.The rotational inertia of the combination is I.A string is wrapped around the larger disk and attached to a block of mass m, on the table.Another string is wrapped around the smaller disk and is pulled with a force as shown.The acceleration of the block is:

A particle moves in a circular path of radius 0.10 m with a constant angular speed of 5 rev/s.The acceleration of the particle is:

A uniform disk, a thin hoop, and a uniform solid sphere, all with the same mass and same outer radius, are each free to rotate about a fixed axis through its center.Assume the hoop is connected to the rotation axis by light spokes.With the objects starting from rest, identical forces are simultaneously applied to the rims, as shown.Rank the objects according to their angular velocities after a given time t, least to greatest.