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A copper rod of mass m rests on two hori...

A copper rod of mass m rests on two horizontal rails distance L apart and carries a current of I from one rail to the other. The coefficient of static friction between rod and rails is `mu_(s)` What are the (a) magnitude and (b) angle (relative to the vertical) of the smallest magnetic field that puts the rod on the verge of sliding?

A

The greatest height of sand pile that can be created is `mu_(s)R`.

B

The greatest height of sand pile that can be created is `R//mu_(s)`

C

Minimum work required to create greatest height sand pile is `(pi)/12 mu_(s)^(2)R^(4) rho g`. Where `rho` is the density of sand volume

D

Sand pile will be in stable equilibrium

Text Solution

Verified by Experts

The correct Answer is:
A, C
From free body diagram of sand particle
`tantheta=mu s =h/R`
work required `=(1/3 pi R^(2)h rhog)h/4`
The system is in unstable equilibrium.
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