advertisement

PHYSICS 1306, QUIZ 3 Chapter 6 July 29, 2002 Partial credit will be LIBERAL, provided that you show your work! USE BACK IF NEEDED! Name: ______________________ Social Security Number ______________________ 1. (10 points) CONCEPTUAL QUESTIONS!! Using complete, grammatically correct, English sentences, answer the following questions: a. State the Work-Energy Principle. You may supplement the sentences with equations if you explain what each symbol in the equations means. b. State the Principle of Conservation of Mechanical Energy. You may supplement the sentences with equations if you explain what each symbol in the equations means. c. In problems on gravitational potential energy, we usually let y be the elevation of the mass in question. It has been stated in class that where we choose the y = 0 point cannot matter for the final answer. Explain why that statement is true. . 2. (20 points) Note: This problem can be solved either using the Newton’s 2 nd Law (Force) methods of Ch. 4 or the Energy Methods of Ch. 6. This is a quiz over Ch. 6, so you are required to USE ENERGY METHODS TO SOLVE THIS PROBLEM! You will receive no credit for using the Force methods of Ch. 4 to solve this problem! You do not need to resolve forces into components to solve this problem!! See figure. A block of mass m = 300 kg, initially at rest, slides down a frictionless inclined plane. The initial height is h = 5 m above the floor. The incline angle is 37. a. What is the gravitational potential energy of the block at its initial position? How much work must be done by gravity to move the block down the incline? b. What is the kinetic energy of the block at the bottom of the incline? What is its speed at the bottom of the incline? c. What are the kinetic energy and speed of the block when it is 3 m above the floor?