If something is lifted up by a magnet does it weight anything?

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Like for example if i made a track with magnets strong enough to lift a cart (like 4 inches off the ground) . Which i also put magnets underneath and try to push it. How much force would i have to put in compared to a cart with wheels. Lets say the cart is 80kg (if that helps or matters at all)

In: Physics

2 Answers

Anonymous 0 Comments

If I understand you correct, you wanna know how much force you need to move a car floating (via magnets), compared to a car on wheels across a street?

If you do it right, the floating car will need significantly less force, as you have lower friction. How much less depends on the materials use and is not so easy to say.

However you will still need force to overcome inertia and accelerate the mass of the car (as it still have mass). but that is normally not the big issue for vehicles, as you only need to do that once to get to a certain speed, and afterwards you only need to compensate for friction (which is low in you magnetiv levitation setup).

Basically you have invented a maglev train.

However in reality that is really expensive and even letting an object just levitate is really complicated. Therefore it is not really widespread and only really efficient for high speed trains

Anonymous 0 Comments

Weight is an abstract of the force of gravity weight = f = mg.

Yes the 80kg cart still exerts force downwards, gravity (9.8ms²) still acts on it and it still has mass (80kg)

If you limit the system your looking at to ignore the magnet construct that supports it then it might look like magic and that it is ignoring gravity, but if you include the magnet in your system then it’s that the magnet has taken on the weight of the cart.

The cart pushes down on the magnet and the magnet pushes down on whatever it’s resting on

The magnet will have a force of the magnet + cart pushing down on whatever the magnet is resting on

If you had two boxes, one stacked on the other, you wouldn’t say the top one has no weight, if you tried to pick them both up at once you would realize that you’re picking up the weight of both boxes. Similarly, if you tried to pick up the magnet you would realize that you’re picking up the weight of the magnet + floating cart