The Conservation of Momentum Explained Simply

The law of conservation of linear momentum, shown with both Newton's laws and Galilean relativity. Classical mechanics.

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*Script*
Jules Rankin
@jules_rankin

*Animations*
Tom Groenestyn

*Music*

[upandatom]

Which explanation did you prefer, Newton's laws or Galilean Relativity? Why?

[doandrewt]

Animation skills aren't conserved; they are expanding over time!

[saumitrachakravarty]

Momentum comes from the Latin, petere, which is somewhat similar to impetus; hence we get p.

[ukcroupier]

The bit at 9:15 put a big smile on my face. I luv it when something that appears complex can be explained in such a simple way.

[prameshshrestha]

Whats momentum?
Its...um.... oomph😂😂

Couldnt have said it better 😂😂

[MrCardeso]

I was happy to see the Earth having such a blast flying around the Sun!

[akshat]

I have studied this all but I still enjoy watching this #oomph

[arnoahmed]

It was the best video on momentum I've watched. Was confused on this and other YouTubers just started waffling and explaining the same concept in a more "smarter" way to sound smart. Glad you broke the fundamentals down. Thank you so much!

[bingbongtheory]

You should do more on inertial frames of reference. I remember that being a big change in perspective for me personally when conceptualizing physics problems.

[AlexKnauth]

That Relativity argument is really useful. It was useful for me when designing the collision-handling code for a small game I was making. I already had library functions for switching frames-of-reference as Galilean Relativity says, so if I use those to switch to the frame of the center-of-mass, the collision-handling becomes so much simpler because of the symmetry. Then once I find the state after the collision, I switch back to the old frame-of-reference.

[samarthsai]

I read about the relativistic point of view in the feynman lectures, as thrilling it was to read and animate it in my head, it is amazing to watch it animated on screen.Keep up the good work.

[bhanudas]

I just love the way you explain...it is helping we during these online classes....

[loganstrong]

I remember doing collision problems in physics where you find the moving reference frame and conserve momentum. Nobody told me it was called Galilean Relativity, that sounds much cooler!

[animistchannel]

I failed to play along at home. When you got to the part where we could toss something in the air to demonstrate for ourselves, I looked around and what was in reach was: bowl of steaming hot oatmeal, cup of steaming hot coffee, my desktop computer, some delicate and pointy diagramming tools, and a stack of papers full of nautical designs. It just didn't seem like a good personal experiment at the time, so I'll have to take your word for it about the conservation of momentum.

See, that's what I get for playing science videos with my breakfast -- I'll have to live with my faith in you after all. Fortunately, you have proven to be a credible source of information, which is rare these days. Of course, with boats & ships, we are often more concerned with another related law: "Something in motion tends to remain in motion until acted upon by a force." The goal being to have a vessel that directs force cleverly, and not get it acted upon by a rocky shore. Now, back to work! Row! Row! Row!... err... I mean... Draw! Draw! Draw! :)_

[pixelfairy]

love the multiple approach style of this and the lagrange mechanics one you recently did! its the combination produces more understanding than the sum of the parts

[ayushkumawat]

i prefer Newton's explanation for momentum because the original Newton's second law is based upon momentum and F=ma is derived by that so that clicks better into my mind but Galilean approach can help anyone to assume the concept of momentum and visualize that in real world

[jeremyrixon]

Great video! (As an ex sydneysider, I also appreciated the scenes of Sydney! Whoever thought one could get nostalgic over the Princes Hwy?)

[neelotpaldutta]

You missed a wonderful chance at 1:33, "Now imagine I throw a moon at you".

[Tomyb]

I really liked this video!
Another interesting approach for the Newtonian explanation would be to talk about how an object is able to change its momentum.
After talking about what magnitudes describe momentum (ie mass and velocity), you could talk about how for something to move in the first place you have to push it. Pushing really just means to apply a force for a given amount of time, so you could once again bring attention to the two magnitudes that affect momentum from this perspective (meaning, how a bigger force gives it more "oomph" and how applying a force longer also gives it more "oomph"). Here I would also mention that looking at momentum with this new definition also gives the same units as with the p = m*v definition.
Lastly, you then bring Newton's 3rd law and say that because every force comes in equal and opposite pairs, for every object that got a given amount of "oomph", another got the same but opposite amount of "oomph".

This has always been my favorite way of looking at conservation of momentum, but now that I've seen the relativity way, I think it's growing on me...

[BangMaster]

The letter 'p' is used to refer to momentum, because the letter 'm' is already used for mass in the equation for momentum.
So, if you were to use 'm', the equation would become a bit weird 'm = m*v'. That's why we use 'p = m*v'.