this post was submitted on 11 Dec 2023
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[–] [email protected] 90 points 11 months ago (1 children)

This looks like the magnetic version of pulling yourself up by the bootstraps.

[–] [email protected] 16 points 11 months ago (3 children)

Baron Munchausen would like to have a word

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[–] [email protected] 65 points 11 months ago (3 children)

The car is also made out of metal. Why do you need the metal in front?

[–] [email protected] 62 points 11 months ago

More weight = more magnetic

I don't know.

[–] [email protected] 19 points 11 months ago

The actual metal content varies. With plastic bumpers, aluminum condenser/radiator, composite support pieces, the actual amount of magnetic metal may be quite minimal, and there's practically no vehicles that have so much metal in their front end to compare to a slab of metal on the outside.

[–] [email protected] 9 points 11 months ago (1 children)

Try using a magnet on a can of coke.
"But it's made of metal" he says.

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[–] [email protected] 52 points 11 months ago

Because the hand brake is still pulled, dummie

[–] [email protected] 39 points 11 months ago* (last edited 11 months ago) (1 children)

Issac Newton would like to have a word.

[–] [email protected] 31 points 11 months ago (4 children)
[–] [email protected] 17 points 11 months ago

You dont wana mess with zombie newton.

[–] [email protected] 9 points 11 months ago (5 children)

…serious about the third law of motion

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[–] [email protected] 37 points 11 months ago

Archimedes once said something like: "Give me a big enough lever and a place to stand, and I shall move the Earth."

The "place to stand" part is just as critical as the lever part. You gotta have something to push off of in order to move other things. This is a closed system that pushes and pulls only against itself.

[–] [email protected] 37 points 11 months ago (6 children)
[–] [email protected] 29 points 11 months ago

The brake pedal slides an opposite side magnet closer to you.

[–] [email protected] 13 points 11 months ago

Use an electromagnet

[–] [email protected] 4 points 11 months ago

Play an Insane Clown Posse song and the magnet stops working.

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[–] [email protected] 35 points 11 months ago (1 children)

Simple. The magnet weighs less than the car, so the magnet is going to be moving to the left. If the force is going to the left, that means the car can only go in reverse.

[–] [email protected] 15 points 11 months ago (1 children)

So the vehicle just needs turning around for this to work then or.....?

[–] [email protected] 10 points 11 months ago

Nope, unfortunately now the car has been magnetized, and that would swap the polarity, making it move in the opposite direction, which is reverse again.

[–] [email protected] 34 points 11 months ago* (last edited 11 months ago) (2 children)

Back where I'm from the elders used to call this kind of thing "bait for social media interaction"

[–] [email protected] 4 points 11 months ago* (last edited 11 months ago)

Well where I'm from they call it artificially elevated social attraction

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[–] [email protected] 23 points 11 months ago (13 children)

I am a complete idiot and I would also like to know.

[–] [email protected] 68 points 11 months ago* (last edited 11 months ago) (1 children)

Newton's third law. Every action has an equal and opposite reaction.

Basically what that means is if the magnet is exerting some amount of force on the truck to pull it towards it, the truck is exerting the exact same amount of force on the magnet in the opposite direction to pull the magnet closer to the truck. This is why when you let go of two magnets they fly towards each other instead of one staying still (unless you hold it still) and the other flying towards it.

If the arm in the picture could bend, the magnet would just stick to the front bumper. If it couldn't move, the magnet would pull on the plate, but that would be cancelled out by the plate pulling on the magnet. They're trying to attract each other, but neither of them can move, so it just stays still.

Now, if the magnet was attached to a different truck, and that started moving, it would pull the truck along just fine. If the second truck was in neutral, it'd roll backwards and the two trucks would meet in the middle. But if you wanted them both to go, you'd have to turn on the engine in the second truck, and you've effectively just invented the world's least reliable tow hook. You can't cause a car to accelerate without some outside force (the second truck's engine) pulling it along.

Newton's third law also applies to gravity. When the Earth's gravitational pull makes something fall to the ground, that something actually exerts the same amount of force pulling the Earth towards it. The earth is several orders of magnitude heavier, though, so it doesn't move very much. Gravity from the moon pulling on water in the ocean does create the tides, though.

[–] [email protected] 8 points 11 months ago (4 children)

If the arm in the picture could bend, the magnet would just stick to the front bumper

What if the magnet was of similar mass to the truck? Assuming it could be made to balance, maybe this actually might work to move the truck such that it meets the magnet in the middle. Then the arm could slide the magnet upwards to detach, reposition it, and repeat. Of course, there are much better ways to make a truck move, but maybe it could work?

[–] [email protected] 20 points 11 months ago (1 children)

Then the arm could slide the magnet upwards to detach, reposition it, and repeat.

This would work, but this is the point where you'd need to involve an external energy source. If you move the truck-magnet-arm system such that the whole system reaches a steady state and the truck has "moved" (relative to an outside observer), to continue any motion, you need to disturb the steady state to reposition the arm and create a new resting point. Doing so would require energy. From a battery, or an engine, or whatever, but you need energy from an external source. And so we're right back to where we started: instead of all this jazz, why not just spend energy to spin the wheels instead?

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[–] [email protected] 6 points 11 months ago

That could work, yes. You would have to unstick the magnet from the bumper every time -- or alternately just leave it attached and use it as a tow hook -- but it would work

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[–] [email protected] 53 points 11 months ago (1 children)

The magnet pulls the truck to the right. The truck pulls the magnet to the left. They both have the same amount of pull. No one wins this tug-o-war.

[–] [email protected] 5 points 11 months ago

The best you can hope for is for the truck to move slightly to the right and the magnet to move far to the left until they meet

[–] [email protected] 20 points 11 months ago (4 children)

Because the magnet is attached to the truck bed, so the bumper is being pulled forward and the bed pushed back, and the forces cancel out to 0.

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[–] [email protected] 10 points 11 months ago

Newtons laws of motion, most clearly the third.

"If two bodies exert forces on each other, these forces have the same magnitude but opposite directions."

[–] [email protected] 6 points 11 months ago* (last edited 11 months ago)

In simple terms: metal is just as much attracted to magnet as magnet is to metal, this is fundamental and doesn't change under any circumstances.

So the force driving the car forward is exactly equal to the force driving the car backward, and you can't have one without the other.

[–] [email protected] 4 points 11 months ago (1 children)

The truck will be attracted forward towards the magnet, but the magnet will also be attracted backward towards the truck with equal force. The backward force will be transfered through the arm holding the magnet and the net force on the whole system will be 0. If there was no arm holding the truck and the magnet apart, the truck could move forward slightly and the magnet could move backward to meet it. (The magnet would move much more than the truck since they would still have equal force applying to them, and the truck's mass is much higher than the magnet's.)

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[–] SushiRollington 20 points 11 months ago (1 children)

Because the truck wouldn't be loud and obnoxious so no Truck person would ever drive it

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[–] [email protected] 20 points 11 months ago

Newton’s third law would like to have a word with you 🫠

[–] [email protected] 19 points 11 months ago (1 children)

This is basically how you build a warp drive in Kerbal Space Program

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[–] [email protected] 16 points 11 months ago (1 children)

Why put metal in front of a car that‘s made out of… metal?

[–] [email protected] 30 points 11 months ago
[–] [email protected] 15 points 11 months ago (1 children)
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[–] [email protected] 12 points 11 months ago

The force pulling the car to the magnet is the same as the magnet pulling towards the car. These two forces cancel out each other.

[–] [email protected] 11 points 11 months ago

Ok one reason… physics.

[–] [email protected] 11 points 11 months ago* (last edited 11 months ago)

It would work much better with a carrot and a pig.

https://youtu.be/3hPboNpHKfw

[–] [email protected] 7 points 11 months ago

Draw a force diagram. Then bing perpetual machines.

[–] [email protected] 7 points 11 months ago (1 children)

Why do you put metal on front? The car is already metalic

[–] [email protected] 5 points 11 months ago (2 children)
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[–] [email protected] 6 points 11 months ago

Conservation of momentum

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