# Electromagnetism's repulsive force

1. Jan 13, 2016

### jabes

can a electromagnet's repulsive force be made powerful enough to be able to push another electromagnet bearing a weight of 5 tons??

2. Jan 13, 2016

### Bystander

Yes.

3. Jan 13, 2016

### jabes

then, can it be done by 2 car batteries alone??

4. Jan 13, 2016

### Bystander

For how long a time?

5. Jan 13, 2016

### jabes

as long as possible for the battery to do so, but at-least 15-20 hours.

Last edited: Jan 13, 2016
6. Jan 13, 2016

### Bystander

Two car batteries @ 500 amp-hrs x 12 V is 21.6 MJ x 2. Five ton force? What displacement distance? What gap?

7. Jan 14, 2016

### jabes

yes five tons of force, and for displacement instead of linear momentum i want circular momentum and the gap could be anywhere between 0.5 to 1.5 cm, between the two magnets.

8. Jan 14, 2016

### Bystander

I've played along enough to give you some idea how this forum works --- now's the time for you to put in some effort.

9. Jan 14, 2016

### gleem

This is a non trivial problem. Two typical car batteries connected in parallel will have about 200 amp hr capacity. That number is based on drawing the current over a 20 hr period. So you can draw 10 amps for 20 hrs. But if you draw more current it will last much less time than this number predicts. See Peukert's Law

Think how long you can continuously crank your car engine before you exhaust the battery and double that since you are using two batteries. I'm betting less than 4 minutes.

You need to determine the physical size of the magnet, the core material, the number of turns in the coils. I think it will be a significant part of the load which you want to support. Do you know how the force is related to the properties of the magnets?

10. Jan 14, 2016

### jabes

Bystander: i think, i have got a general idea about what is to be done.so, thanks for the help. it really means a lot to me.

11. Jan 14, 2016

### jabes

gleem: yes, i more or less know about the relationship between force and the properties of the magnets.so, i think i will take it from here, thank's a lot for the help. now that the theory is complete, i can finally get to do some real work.

12. Jan 14, 2016

### Staff: Mentor

Horizontally on a low friction surface, or vertically in opposition to gravity?

In either case, it will certainly push, but in the latter it may be difficult for you to construct something that will initiate movement.

13. Jan 15, 2016