1. Physics 218: Mechanics Instructor: Dr. Tatiana Erukhimova Lecture 15

2. Massless, unstretchable string; frictionless pulley Force of tension

4. Block 1, of mass m 1, is placed at rest on an inclined plane. It is attached by a massless, unstretchable string to block 2, of mass m 2. The pulley is massless and frictionless and just changes the direction of the tension in the string. The coefficient of friction between the plane and m 1 is the constant . 2 1 Determine what range of values for mass m 2 will keep the system at rest. Find acceleration if mass 2 goes down.

5. F Find F necessary to drag the box 1 at constant speed. 1 2 Friction everywhere.

6. The advantage of a pulley What minimum force F is needed to lift the piano of mass M?