International Physics olympiad problem

shekhar_dandya

Jun 18, 2004
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Jun 18, 2004
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solve this international olympiad prob

suppose a cylinder of weight 20N is rolling on ground in right direction.if half of length of cylinder is positively charged,and it is placed in magnetic field whose dirction is inward to plane of rolling and if a charged particle is placed at distance 10m from cylinder .and magnitude of electrical interacton is 10N
and magnitude of magnetic field force is 31N.
will cylinder fly?
if yes ..then in which direction  ?

I tried to solve this:
Basically the cylender will fly if normal component of net force acting on cylender
is > 20N.
I found many things missing in the above problem or they need to be assumed:
1.Polarity and magnitude of charge(+ve/-ve)?
  if we use F = q1q2/r2(coloumb's law) how to find q1,q2?
2.Placement of charge in 3-D space?
3.The mechanical force acting on the cylender due to magnetic field:
  F = BILsin(x).
How to find B from magnetomotive force?
  B = uH
  H = mmf/(leghth of coil).How to find this?

4.The velocity at which cylender is rolling?From this we could find the current i.e
  rate at which charge is moving.
I think x = 90 deg so sin(x) = 1.

Any thoughts?
-Shekhar

 
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