Magnet and gree energy

  • #1
magnet and free energy

when i stick a magnet on a fridge it willl eventually slide down and fall of due the domains in the mganet nuetralizing each other out right ?

Now my question is does the energy reuiqred to realign the the magnet to its original strength = the amount of enrgy that is requireed to keep that magnet against the fridge working against gravity for the length of time unitll it falls off

seems like more energy to keep magnet on fridge thatn to realign it
 
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Answers and Replies

  • #2
Gza
444
0
Conservation of energy would deem your assumption false.
 
  • #3
krab
Science Advisor
893
3
bozo the clown said:
the amount of enrgy that is requireed to keep that magnet against the fridge working against gravity for the length of time unitll it falls off
That amount is zero. A constant force does not imply an expenditure of energy.
 
  • #4
krab said:
That amount is zero. A constant force does not imply an expenditure of energy.

im confused if I physically hold the magnet that fell off ; agaisnt the fridge myself instead of magnetizing it am I not expending energy
 
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  • #5
Gza
444
0
Energy changes in a physical system are caused by work. Work is defined as a force over a distance. If you hold a magnet in place without moving it, there is no possible way work can be done, therefore no expenditure, or for that matter, absorption of energy.
 
  • #6
russ_watters
Mentor
21,197
8,011
bozo the clown said:
im confused if I physically hold the magnet that fell off ; agaisnt the fridge myself instead of magnetizing it am I not expending energy
Your body expends energy doing anything. But you are not imparting any energy onto the magnet by holding it against the fridge.
 
  • #7
ok understand now
 

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