- #1
chikis
- 237
- 1
Homework Statement
A stone of mass 5 g is projected with a rubber catapult. If the catapult is streched through a distance of 7 cm by an average force of 70 N, calculate the instantaneous velocity of the stone when released.
Homework Equations
work done in elastic material w = 1/2 fe = 1/2 ke2 = 1/2 mv2 - the kinetic energy of the moving stone.
(a) 1/2 fe = 1/2 mv2
Or
(b) 1/2 ke2 = 1/2 mv2
The Attempt at a Solution
mass m = 5g = 0.005kg; extension e = 7cm = 0.07m;
force f = 70 N; velocity = ?;
using:
1/2 fe = 1/2 mv2
v = square root ( fe/m)
v = (70 * 0.07/0.005)
= 31. 304 m/s
Using either of the equations gives the same result. Am not sure wether I have arrived because the book am using gave a different solution for the problem. So you watching at this thread, what do you think?