# How to verify my ballistic pendulum calculations (please read if you have a newtons cradle)?

I don't have a newtons cradle but we are theoretically using one to do a ballistic pendulum lab. We are supposed to show through calculations how the conservation of energy works and how the conservation of momentum works. I fudged my numbers because I do not have a newtons cradle. My numbers are:

Mass = 0.025 g

height = 0.1 m

From there I calculated the initial velocity of the ball before it hits the other balls with the conservation of energy using Eg = Ek. I got:

V = 1.4

Then I proved that momentum is conserved by using the conservation of momentum where mv = mv and showed that velocity stays the same. I then proved that the height of the final ball would reach the same height as the initial ball had by using conservation of energy again.

My lab asked for:

In your choice of experiment, theoretically calculate what the end result should be (height of the cradle, compression of the spring, range of the projectile), and then verify
that calculation experimentally.

Does my calculations prove that? Should I just make up a number and say that it was the "height" of the final ball that I measured?

If anyone has a newtons cradle, could you please weigh one of the metal balls and then measure the height of how high you dropped the metal ball and then roughly measure how high the final ball went?

• This is more appropriate for physics stackexchange – Triatticus Apr 20 '18 at 21:01
• You should trust physics laws. A newton cradle almost 100% demonstrates elastic collision. As long as you applied the laws correctly, the experimental result is going to be very close to your theoretical value. – Szeto Apr 20 '18 at 22:34