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Physics 311, Quiz #13

What are the units of torque?

Question 1: The kinetic energy of the system is

  1. N * s
  2. kg * m^2 / s^2
  3. kg^2 * m / s^2 
  Answer:   b, the same as Newtons * meters.

Question 2: A door is exactly 1 m wide. Fred pushes the center of the door with a force of 30 N. How much torque does Fred exert around the hinges of the door? 

  Answer:   Torque = (lever arm) * (Force)

                   =  0.5 meter  *  30 N 

                   =  15 N*m

            Note that the CENTER of a door 1 m wide is only 0.5 m
            away from the hinges.  Fred would exert a greater torque
            by pushing the side of the door opposite the hinges...

This page maintained by Michael Richmond. Last modified Feb 19, 2002.

Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.