View Full Version : magnet and gree energy
bozo the clown
Jul13-04, 12:56 AM
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
Conservation of energy would deem your assumption false.
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.
bozo the clown
Jul13-04, 01:32 AM
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
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.
russ_watters
Jul13-04, 08:16 AM
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.
bozo the clown
Jul13-04, 09:11 AM
ok understand now
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