Rotational Dynamics
Problems
Problem : Calculate the net torque exerted by F 1 = 30 N and F 2 = 50 N in the figure below. You may assume that both forces act on a single rigid body.
Problem :
Two cylinders of the same mass and shape, one hollow and one solid, are set on a incline and allowed to roll down. Which cylinder will reach the bottom of the incline first? Why?
Problem :
A simple pendulum of mass m on a string of radius r is displaced from vertical by an angle θ , as shown below. What is the torque provided by gravity at that point?
Problem :
See the last problem. What is the angular acceleration of the pendulum at that point?
Problem :
A revolving door is common in office buildings. What is the magnitude of the
torque exerted on a revolving door of mass 100 kg if two people push on opposite
sides of the door with a force of 50 N at a distance of 1 m from the axis of the
door, as shown below? Also, the moment of inertia of a revolving door is given
by
I =
. Find the resultant angular acceleration assuming no
resistance.
=
=
τ = 100
=
rad/s2




