Calculating Total Energy Loss of a Newton's Cradle

[faunmia]

How can I measure the total energy loss of a Newton's cradle until it comes to rest. The only variables I am given are the horiztonal displacements for each swing (how far the ball travels out after it rebounds off the other balls) and the angle. I have no idea where to start, I was told I should be able to work out velocity from the displacements and gravity(9.8m/s). The equations I have are
KE = mv²/2
p = mv
I am not asking for anyone to do this for me, but rather a starting point which I can work from

 

[lavalamp]

Calculate the maximum vertical displacement of the ball, from that you can calculate the maximum gravitational potential energy, when it's kinetic energy is zero.

When the system comes to rest, it will have no kinetic energy and it will be at it's minimum gravitational potential energy.

The difference between the two therefore, is the value you calculate for GPE.

 

[Feldoh]

Adding to lavalamp, the only energy that was added was the work you did on the first ball to give it potential. The system certainly is not gaining any mechanical energy once you release the first ball.