- #1
WahooMan
- 22
- 0
Homework Statement
A 30g rifle bullet traveling 220 m/s buries itself in a 3.0kg pendulum hanging on a 2.1m long string, which makes the pendulum swing upward in an arc. Determine the vertical and horizontal components of the pendulum's maximum displacement.
Homework Equations
p=mv
K=1/2mv^2
Ug=mgy
The Attempt at a Solution
First, I found the momentum of the bullet:
p=mv
p=(0.03kg)(200m/s)
p=6.6kg*m/s
Then I found the velocity of the pendulum after the bullet hits it:
(6.6kg*m/s)/(3.03kg)=2.18m/s
After that I found the Kinetic Energy of the system just after the bullet hits the pendulum:
KE=1/2mv^2
KE=(1/2)(3.03)(2.18)^2
KE=7.19J
Then, because that Kinetic Energy transfers to Gravitational Potential Energy when the pendulum has reached its max height, I set the Kinetic Energy equal to Gravitational Potential Energy.
Ug=mgy
7.19J=(3.03kg)(9.80)(y)
y=0.24m
Using the length of the pendulum (2.1m) as the hypotenuse and (length of the pendulum - y=1.86m) as the y component, I used the Pythagorean Thereom to solve for the x component.
a^2+b^2=c^2
1.86^2+b^2=2.1^2
b^2=2.1^2-1.86^2
b=0.98m
So I got the x component to be 0.98m and the y component to be 1.9m, but MasteringPhysics says I'm wrong. What did I do wrong?