PHYS 1081 Written Assignment 3 Due: Start of class Monday Dec. 7, 2015

General Instructions:

• The assignment should be submitted on 8.5 × 11 inch paper with a cover sheet giving your name, the date, the course and the assignment number. In the upper right hand corner of the cover page create a 1 inch by 1 inch square and in this square place the first letter of your last name (as recognized by UNB).

• The assignment will be graded (in part) on presentation. Please be neat and organized. Define coordinate systems as needed.

Problems:

1. The spring in the following figure has a spring constant of 1000 N/m. It is compressed 15 cm, then launches a 200 g block. The horizontal surface is frictionless, but the block’s coefficient of kinetic friction on the incline is 0.20. What distance d does the block sail through the air? (Problem 73, Chapter 11, Physics for Scientists and Engineers 3rd ed. by Randall Knight, Pearson)

2. A uniform spherical shell of mass M = 4.5 kg and radius R = 8.5 cm can rotate about a vertical axis on frictionless bearings. A massless cord passes around the equator of the shell, over a pulley of rotational inertia I = 3.0 × 10-3 kg･m2 and radius r = 5.0 cm, and is

attached to a small object of mass m = 0.60 kg. There is no friction on the pulley’s axle; the cord does not slip on the pulley. a. What is the speed of the object when it has fallen 82 cm after being released from rest? Use energy considerations. b. What is the angular acceleration of the sphere?(adapted from Problem 66, Chapter 10, Fundamentals of Physics 8th ed. by Jearl Walker, Wiley)