How High Will the Bullet-Carrying Cart Climb the Ramp?

[runningirl]

Homework Statement

At a crime lab, they are experimenting measuring the speed of bullets. In it, a 15 g bullet is fired at 150 m/s into a wood block mounted on a low-friction cart (m=0.5kg). The bullet imbeds in the cart and the cart then rolls up a 30-degree ramp. Ignoring friction, predict the max height that the cart will rise to as it rolls up the lamp.

Homework Equations

The Attempt at a Solution

.015(150)+0=(.5+.015)vx

vx=4.37 ms

since it's a 30 degree angle.. the velocity of cart=4.37/cos(30)=5.04 m/s

x=(vf^2-vo^2)/2a
=(5.04^2-0)/2(9.8)
-1.2?

i don't know if this was correct.

 

[Mindscrape]

Why not just say mgh=.5m(vx)^2

h = sqrt(4.37^2/20)