Energy Loss in a Collision: Calculating Speed and Percentage

[brunettegurl]

Homework Statement

A 40.8 g ball of clay hits and sticks to a 3.41 kg block sitting at rest on a frictionless surface. What is the speed of the block after the collision if the initial speed of the ball of clay is 5.04 m/s?
b)What percentage of the system's initial energy is lost?

Homework Equations

pinitial=pfinal, E=0.5mv²

The Attempt at a Solution

for the first part i figured out the speed final which is 0.0596 m/s
for the second part for each i figured the initial energy and then the final energy using the energy equation for both objects involved. after this part i am stuck to figure out the energy lost i came up with this equation 100-(E_initial-E_final/E_final) x100.. i used it and am not getting the right answer..pls. help

 

[diazona]

Divide by initial energy, not final energy (that's what it means by "percentage of the initial energy").

 

[brunettegurl]

thanks :)