Best Film on Newton's Third Law. Ever.

There are a lot of misconceptions out there, and this is a video about one of the most common ones. So I went around asking people, "What makes the Moon go around the Earth?" and they told me, "The Earth puts a gravitational force on the moon."

But does the moon put a gravitational pull on the Earth? Pull on the Earth, yes. It does; hence we have tides, etc. The moon falls on the Earth, too; it affects like the tides and women, and yes, it does very powerful.

Does the moon pull on the Earth? Probably, that as well. Yeah. So what I want to know is how does that force that the moon exerts on the Earth—how does that compare in terms of size to the force the Earth exerts on the moon?

Well... No scientist, but I think that one would be more powerful than that one. It's got a greater force coming from the Earth because it's greater mass. The Earth has more mass [cuz] it's a bigger mess. I thought greater mass is more [equals] more force [guys].

Does the moon pull on the Earth? Yes. But a lot less. Yeah, not as much as the Earth pulls on the moon. Yeah. Yeah, but a little bit, not [very] strongly. Yes. But much, much, much, much smaller. Because if it's mass [less], [not] size. Because it's smaller. It's much smaller than [that], than the Earth because it's smaller.

This is small. Allow me to let you in on a little secret. Everyone got it wrong. The force that attracts the moon to the Earth is exactly the same size as the force that attracts the Earth to the moon.

So what's going on here? Why did everyone get it wrong? Well, I think it comes down to cause and effect. The effect of the force on the moon is quite clear; the moon goes in circles around the Earth. But the effect of that force on the Earth is basically negligible; the Earth barely wobbles at all.

So people interpret this negligible effect as indicating there's very little force affecting the Earth. But that is forgetting the third key piece of the puzzle, which is inertia. Inertia is the tendency of mass to maintain a state of motion. Since the Earth has a greater mass, it has a greater inertia.

And so even with the same amount of force on it, it doesn't accelerate that much. Now, the funny thing is many of the [people] I interviewed could state Newton's third law, which is: every [force] has an equal and opposite reaction.

Something about Newton's law doesn't seem to fit into that just yet. You're good at this! Wait, which Newton's law are we talking about—the whole equal and opposite force thing? Yeah, that one. So tell me what you're thinking, man.

[Ah], well, did one would think that if you're into putting a force on me, I would be putting an equal force upon it? So why didn't they apply it to this problem? Well, I think they may have memorized the words, but not really [believed] Newton's third law in their core. Did they really feel it in their spleen? [I] don't think they did.

So allow me to try to convince you, all of you, spleen included, that Newton's third law really is true. Let's consider two objects. Initially, they have the same mass: 1 kilogram each. So obviously, the gravitational force of attraction must be the same on both of the objects.

Now let's add a second kilogram to the first object. The force on the second object will now be twice as great because that 1 kilogram is attracted equally to each of the kilograms in the first object. But what is often forgotten is that new kilogram is also attracted to the second object, meaning that the total force on each object is still the same. They're attracted to each other with an equal and opposite force.

We could add a third kilogram, and we would find the same thing; the force on both objects is still the same, even though the object on the left has [3] times the mass of the object on the right.

So we can see that no matter what the mass, any two objects will have the same gravitational force towards each other. Can you feel Newton's third law in your spleen now? It should settle inside you and become a part of you.