1. a Weekend Plumber, Unable to Loosen a Pipe Fitting, Slips a Piece of Scrap Pipe Over

Handout Title: Lecture 14 Leader: Ross Westercamp Subtitle: SI 2/29/2012 Course: Physics 111 Supplemental Instruction Instructor: Dr. Alan Goldman Iowa State University Date: February 29, 2012

1. A weekend plumber, unable to loosen a pipe fitting, slips a piece of scrap pipe over his wrench handle. He then applies his full weight of 900 N to the end of the pipe by standing on it. The distance from the center of the fitting to the point where the weight acts is .80 m, and the wrench handle and pipe make an angle of 19 degrees with the horizontal.

a. Find the magnitude and direction of the torque he applies.

2. We wrap a light, flexible cable around a solid cylinder with mass M and radius R. The cylinder rotates with negligible friction about a stationary horizontal axis. We tie the free end of the cable to a block of mass m and release the object with no initial velocity at a distance h above the floor. As the block falls, the cable unwinds without stretching or slipping, turning the cylinder.

a. Find the acceleration of the block of mass m.

3. Four forces of equal magnitude are applied separately to the edge of a thin square plate as shown. The forces and the plate lie in the plane of this page. Which one of the four forces shown exerts the greatest magnitude of its torque on the plate about the point at the center of the plate?

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