- #1
Mr Davis 97
- 1,462
- 44
Homework Statement
[/B]
An archer pulls a bowstring back 0.440 m, and the spring constant of the bow is 545 N/m. Find the amount of work the archer did to draw the bow.
Homework Equations
[/B]
F = ma
Ei = Ef
The Attempt at a Solution
[/B]
It seems as though there are two ways of doing this: using Newton's laws or using conservation of energy.
a) Newton's laws:
W = Fd
F = -kx = 240 N
d = 0.440 m
W = Fd = 106 J
b) Conservation of energy
Ei = Ef
Wapply = Ufinal
Wapply = (1/2)kx2 = 53 J
As one can see, these are two different answers. In fact, the latter is exactly half of the former. What am I doing wrong? Is either answer even right?