PHYSICS 1306, QUIZ 3
Chapter 6
July 28, 2003
Partial credit will be LIBERAL, provided that you show your work! USE BACK IF NEEDED!
Name: ______________________ Social Security Number ______________________
1.
2.
(10 points) CONCEPTUAL QUESTIONS!! Using complete, grammatically correct, English
sentences, answer the following questions:
a. Define the work done by a constant force. If you write an equation, explain what each symbol in
the equation means.
b.
State the Work-Energy Principle. You may supplement the sentences with equations if you
explain what each symbol in the equations means.
c.
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.
(20 points) See figure. A toy gun uses an ideal, stiff spring to shoot darts. The spring constant is
k = 300 N/m. Neglect the dart’s gravitational potential energy in this problem.
v=0
v=?


x = 0.2 m
Before shooting
x=0
After shooting
a.
When the gun is cocked, the spring is compressed a distance x = 0.2 m. Compute the elastic
potential energy of the spring when the gun is cocked.
b.
If the gun shoots a dart of mass m = 0.3 kg, compute the kinetic energy of the dart just after it
leaves the barrel. What physical principle did you use to find this result?
c.
Compute the speed of the dart just after it leaves the barrel.