need to be able to pull 11ish tons of string to ring the bell
But the weight of the string isn’t the force you need to pull.
Comment on The Planet, some string and a bell.
BrotherL0v3@lemmy.world 1 year ago
I did some numbers because it sounded fun.
Earth’s diameter is 41.804 million feet. I’m not sure if you meant that or Earth’s circumference when you said “Earth’s surface”, but I figure either one is gonna get us a really big number.
The first result I can find for string comes in a pack that weighs 2.89oz and contains 328 feet of string.
Using that as our standard, you would need 127,452 packs of string (assuming you find a way to perfectly attach them without wasting any length on knots).
127,452 * (2.89 / 16) = 23,021 lbs of string total.
So if we ignore the string stretching, compressing, or breaking, you’d only need to be able to pull 11ish tons of string to ring the bell!
NeoNachtwaechter@lemmy.world 1 year ago
sanguinepar@lemmy.world 1 year ago
Why not? If I try to pull a toy car alomg using a big thick rope, the weight of the rope is relevant, not just the weight of the toy car.
NeoNachtwaechter@lemmy.world 1 year ago
Why not?
When you want to lift it up vertically, then the force that you need is exactly the same as the weight.
But when you push or pull it forward, you need a different force.
Push a golf ball on the table: you need very small force, much less than it’s weight. Suck the same golf ball through a garden hose: you need much more force.
You want to look up “coefficient of friction” in your books.
Sethayy@sh.itjust.works 1 year ago
The force of friction is dependent on its weight (or more specifically the force of normal) but not only its weight
Zippy@lemmy.world 1 year ago
It kind of is. That is still 11 tons of mass. To ring a bell, you need to create some velocity on the striker. Pull a 11 ton mass in a frictionless environment will result in an extremely slow rate of acceleration. But in the spirit of the post, I suspect they are not considering how hard they are ringing the bell.
You are technically right though. Even blowing on a string long enough and you could accelerate it up to speeds approaching that of light. Providing there is no friction.
perviouslyiner@lemm.ee 1 year ago
Why would you use packs of string? Just leave the manufacturing machine running and don’t cut it into packs.
NeoNachtwaechter@lemmy.world 1 year ago
It is true in principle. But the speed of sound is different, depending on the material. For that string we can assume it to be roughly 10 times faster than in the air.
~ 1 hour then.
piecar@lemm.ee 1 year ago
Wouldn’t the motion of the string move at the speed of the pull!? Assuming no compression.
NeoNachtwaechter@lemmy.world 1 year ago
Compression and expansion is real. The first part of the string moves with your hand, at the same speed as your hand moves. But then it takes some time until further parts of the string - or the final part of the string - even start with their motion. Ok? And here we were talking about how fast this “beginning of the motion” travels forward through the string. That’s the speed of sound.
TheActualDevil@lemmy.world 1 year ago
Okay, but what if there is no compression or expansion? What if it’s a rigid string already stretched out just enough to be expanded completely but not enough to move the bell? Or maybe a thin wire of the same weight?