When a magnet is made to fall free in air, it falls with an acceleration of 9.8m/s2 but when it is made to fall through a long aluminium cylinder, its acceleration decreases, bec.
a) a part of gravitational potential energy is lost in heating the magnet
b) a part of gravitational potential energy is lost in heating the cylinder
c) experiment was done in northern hemisphere
d) the cylinder shields the gravitational force.

Question

When a magnet is made to fall free in air, it falls with an acceleration of 9.8m/s2 but when it is made to fall through a long aluminium cylinder, its acceleration decreases, bec.
a) a part of gravitational potential energy is lost in heating the magnet
b) a part of gravitational potential energy is lost in heating the cylinder
c) experiment was done in northern hemisphere
d) the cylinder shields the gravitational force.

anonymous · Answer

i don't know which one of the above is correct but i can tell you that, it slows down because the magnet is attracted to the aluminum cylinder and that slows down the fall, but it will still fall as the acceleration due to gravity is higher than the attraction to the cylinder

anonymous · Answer

the energy is used in heating both the cylinder and magnet

anonymous · Answer

that makes sense

anonymous · Answer

@santistebanc there no such option

anonymous · Answer

it is like friction, both objects receive energy

anonymous · Answer

so answer is a and b

vincent-lyon.fr · Answer

Whatever the answer, a magnet is NOT attracted to aluminium.
@nazima: you should tell us what you have already thought of the question. Have you ruled out any answers? Even if you do not know the physical concept at work here, some of the answers are logical, others are absurd.

OS is supposed to be collaborative, not just "please answer that question for me!"

anonymous · Answer

haha, there goes my attempt to help, thanks for correcting me.

anonymous · Answer

I think the answer is B, because aluminium is a conductor, when magnet moves near it, it induces current which generates  heat. But why magnet starts to decrease the acceleration because induced current creates around itself magnetic field which resists magnet's movement. You can learn Lenz's law for further information.

anonymous · Answer

@ArchiePhysics is absolutely correct :)

anonymous · Answer

Thanks for the medals:)

anonymous · Answer

@ArchiePhysics thanku it really helped.

anonymous · Answer

You are welcome!:)

egenriether · Answer

FYI there are good videos of this phenomenon (Lenz's Law) on youtube.  If the magnet is strong enough and dropped through a non magnetic conducting tube it can be made to fall extremely slow.  I have a very powerful neodymium magnet that takes over 10 seconds to fall through a roll of aluminum foil.

egenriether · Answer

http://www.youtube.com/watch?v=E97CYWlALEs Check it out!