# Impulse output

• @Murtaza what is the "impulse" output from the collision behaviors for?

• It's basically how hard it got hit, or how hard it's getting hit over time.

In real physics words, it's the change of momentum over time.

• @Hamed what units is the measurement?
When I was playing around with it, I'd sometimes get a number with a -354 or something on the end, why? I also got just plain words(it was like nan or nah or something) what do they mean?
Also, when the object was just sitting on the other object, there was still a number.

I noticed that the collision point for the while colliding behavior is always the point that it collided at, and won't change if the object rotates while they are colliding.

Also, a while back, I tried to make a newtons cradle, but it wouldn't work right. Will the physics engine work for it? Or does it just not support things like that?

• Nan is probably "not a number" which basically means infinity.

• NaN means not a number like @Aidan-Oxley says.

I've built a newtons cradle, just make sure to set no air resistance so there is no energy lost and set bounciness to a number on each ball.

I believe the units of measurement is Newton seconds.

• @Hamed said in Impulse output:

NaN means not a number like @Aidan-Oxley says.

I've built a newtons cradle, just make sure to set no air resistance so there is no energy lost and set bounciness to a number on each ball.

I believe the units of measurement is Newton seconds.

If you set air resistance to 0, that will make the Newton's cradle a perpetual motion machine, right @Hamed?

• Yes, it should never stop. That being said, the physics engine isn't perfect and there maybe a loss of energy somewhere through a rounding error.