Momentum Blog

For this blog, I decided to demonstrate the conservation of momentum by examining the collision of 2 balls. I was unable to find any small balls around my house, but I was able to find 2 of my brother's old bakugan toys.

Perfect. I would say that each ball weighed approximately 20g.

Seeing that there was still icy snow outside, I decided to utilize it. Another plus: I would receive bonus points!! I found a patch of untouched ice and packed it down, then sprinkled some cold water on it, leaving it to ice over for a few hours. This was to try to get the coefficient of friction lower and successfully demonstrate the conservation of momentum.

Then, I took the balls and rolled them directly towards each other. After a numerous amount of tries, I finally was able to get them to hit and bounce off each other. Here's a short video:

Then, I plugged this video into Logger Pro and calculated both ball's average initial and final velocity. Here's what I got:

Red ball:

Vi = 0.96 right

Vf = -0.71 left

Blue ball:

Vi = 1.76 left

Vf = -0.16 right

With this, I can use the equation M1V1 + M2V2 = M1fV1f + M2fV2f to compare the initial and final momentum. If they are equal, the conservation of momentum is successfully demonstrated.

As you can see, the initial and final values are very similar. The difference is most likely due to errors in calculating the velocities, since they are probably not precise. Other factors that may have caused this slight difference is the friction from the ice the balls rolled on.


This type of collision is an elastic collision since the balls bounce after the collision. In an elastic collision, the kinetic energy is conserved. Here is the calculations of the kinetic energy lost in this collision.

Since this is an elastic collision, there should not be any kinetic energy lost from the collision, but according to this, there was kinetic energy lost. This is most likely again due to the errors in measurements such as the exact velocity.

Perfectly demonstrating the conservation of momentum in a non perfect world is nearly impossible, but my calculations were close and I was able to determine how much energy was lost, since the collision was not a perfectly elastic collision. Let's just take a moment(um) because we are at the end of this blog post now and I can go to bed.