Name: The Physics of Slingshots, with Jörg - Smarter Every Day 31
Uploaded: 2020-03-26T02:45:48.000Z
Duration: 3 min 39 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Hey it's me, Destin. Welcome to Smarter Every Day.

Welcome to the Slingshot Channel. [Laughs]

(Destin) As you can see, today I've been taken over by Germans.

So why do they call your channel the Slingshot Channel? I don't understand.

(Jörg) You know, I don't understand either.

You know, you would think that we'd call it the Nice Guys Channel

or something like that, so... No, they called it the Slingshot Channel.

We're going to talk about the energy use in bands.

- Yes. Well, this is of course the lightest slingshot that I've ever built.

Not exactly. It's actually the most powerful one.

The energy of a rifle shot, and it has the momentum of a sledgehammer.

- Alright, so we'll do the math and see if Jörg is right.

So let's look at the physics of slingshots.

Kinetic energy is 1/2 mass times velocity squared.

but for a Springfield .30-06 it's 3841 joules.

I calculated the momentum of a sledgehammer by smashing bricks in the back yard

It worked out to about 46 newton seconds.

There is an angle between the band and the point of anchoring.

This angle... I'm not going to get my hand in there, 'cause I don't want to die.

But this angle... if you take the cosine of that angle,

that is the amount of force going into accelerating the projectile.

So the closer the bands, the more efficient the slingshot.

and also we kept the bands in drawn out condition for quite a while,

because the rubber was a little bit tired already,

and in cold weather rubber doesn't work as well as in hot temperatures.

It was almost a complete momentum transfer between that ball and the wood.

The mass-times-velocity of the ball went all into the wood,

So the mass-times-velocity of the wood after the shot would be equal to the ball.

So I'm Destin, and you are getting smarter every day.

And if you want to, go check out Jörg's channel - the Slingshot Channel.

so go to his channel and if you like it, subscribe.

(Jörg) This is the only slingshot that I've ever built

that makes grown men giggle like they're small girls.

- Okay, slingshots are all about turning potential energy into kinetic energy.

So the first thing we have to do, is we have to build up the potential energy,

(Jörg) Pretty much. And I will soon be done here, so...

So this is a very, very large steel ball, clasped here between the dowels,

and we're going to try to destroy this pumpkin.

It's just a question of if we can hit it.

Captioning in different languages welcome. Please contact Destin if you can help

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The Physics of Slingshots, with Jörg - Smarter Every Day 31

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