1. Imagine a coin (0.10 kg) sitting on the cover of a book. The coefficient of static friction s between the coin and the book is 0.55. The cover of the book is raised slowly to record the angle at which the coin just begins to slide.

a) Draw a FBD of this system. b) What physical principles should be applied to determine the angle when the coin just begins to slide? c) What equations correspond to these physical principles in part b? d) At what angle does the coin begin to slide? e) When the book is raised to one half this angle, what is the force of static friction?

2. Two masses are suspended by a cord that passes over a pulley with negligible mass. The cord also has negligible mass. One of the masses, m1, has a mass of 7.0 kg and the other mass, m2, has a mass of 3.0 kg. The pulley turns on a shaft through the center of the pulley, which supports the pulley and all the masses. The vertical force of the shaft on the pulley is