PHYSICS 1306, QUIZ 5
Chapter 6
March 26, 2003
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: (You may supplement the sentences with equations if you
explain what each symbol in the equations means).
a. State the Work-Energy Principle.
b.
2.
State the Principle of Conservation of Mechanical Energy. (Note: This is NOT the same as the
Law of Conservation of Energy, which states that energy can neither be created nor destroyed but
can only be transformed from one form to another!).
(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
L
using the methods of Ch. 4 to solve this problem! You do not need to resolve forces into
components to solve this problem!! See figure. A mass m = 50 kg hangs vertically from a long
cord of length L. It is given an initial horizontal velocity v0 = 10 m/s as is shown. It then swings
up to a height h above its initial position, where it stops and turns around. The length L and v
0
the angle  are not needed to solve this problem!
a. Compute (find a numerical value for) the kinetic energy of the mass at its initial position.
How much work must be done against gravity to move it up to the height h?
b.
Compute (find a numerical value for) the gravitational potential energy of the mass at the
height h. Compute the height h.
c.
Compute (find numerical values for) the kinetic energy and speed of the mass when it is at a
height y = 3 m above the initial position.

h
y=0