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True or False: The only way to increase the moment of force is to increase the applied force.
A tale is told from long ago, That rust held fast a nut to bolt, That in its turn in rusty Anvil was held fast. Ancient legends told, they say, That whosoever looseneth The rust-encrusted nut, Be right and proper King. Craftsmen from all the realm Essayed the loosening of The rust-encrusted nut, To thereby claim the throne, But none Had strength enough To budge the thing. No, but with cunning and knowledge you can loosen the nut, Arthur. Use this extra long wrench, and the throne will be yours.
He's the rightwise King of Thisland! Oh, hang on now! Is it easier just because you use an extra long wrench? - Yes. - But -- Look at those muscle-mountains! No way Arthur can pull with a greater force than them. And he doesn't.
But it's not the force that matters, it's the moment of force. You're right, the others are stronger than Arthur and pull with a greater force, but since Arthur has a longer wrench, the moment of force becomes larger. I need to have that explained. Let's explain. The moment of force around a turning point equals the force applied times the distance to the point.
The moment of force around the point A is that distance times that force. If the distance is, say, zero point one meters, and the force is a thousand newtons, what is the moment of force? Yeah... Zero point one times a thousand. One hundred.
One hundred Newton-Meters. That's the unit we use. Newton-Meter. - Shall we look at the wrenches now? - Yes. Now the nut is the turning point. The wrench is zero point one meter long, and sir Fails-a-Lot is really strong.
He pulls the wrench with a thousand newtons. Yeah, he looked kinda buff. Really strong. And he does pull with a great force. But what is the moment of force around the nut?
Hmm... Zero point one meter times a thousand newtons. - That equals a hundred Newton-Meters. - Exactly! Now we're going to compare it to Arthur's wrench. Arthur is pretty weak and only pulls with two hundred and fifty newtons, but he has a wrench that is zero point five meters long. There.
Okay, then the moment is -- zero point five meters times two hundred and fifty newtons. One hundred and twenty five Newton-Meters. Yes! You see? He turns it with a greater moment than Fails-a-Lot.
One hundred and twenty five newton meters is more than a hundred Newton-Meters. And that's enough to loosen the nut. Hey! I get it! And that's why you can see-saw with someone three times your weight.
What do you mean now? Take a look. This is what it looked like when I was a kid, and see-sawed with my dad. Perfect equilibrium, though he weighed three times more than me. Yes.
And why equilibrium? The moment of force, of course. -- Three meters times two hundred and fifty newtons. -- Seven hundred and fifty Newton-Meters on my side. And on your dad's side... -- One meter times seven hundred and fifty newtons. -- Seven hundred and fifty Newton-Meters. It's the same moment of force! That's why we were in equilibrium!
What would happen if your dad moved towards the centre of the see-saw? - I know! - So do I! Do you? The crown is yours, Arthur. Thanks to your knowledge, cunning, and... the moment of force.