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doubt

doubt

by pulkit pandey -
Number of replies: 3

hello

my doubt --

a positively charged sphere of mass  m  is attached by a spring of  k=10000 N/m . The sphere is tied with a thread so that the spring is in its natural length .Another identical , negatively charged sphere is fixed with the floor ,vertically below the 1st charge . Initial separation is  r=50cm and charge on each sphere is  q=100microC. Calculate maximum elongation of spring if string is burnt . g=10.

can this be solved without energy method (like force method ?)

In reply to pulkit pandey

Re: doubt

by Prashanth S -
ELECTROSTATIC FORCE OF ATTRACTION + FORCE DUE TO GRAVITY = FORCE DUE TO SPRING.

(+Q)(-Q)
---------------- + MG = KX
4(PI)E (R²)

MAXIMUM ELONGATION (X)= 36+M
-----
1000




In reply to Prashanth S

Re: doubt

by Varun Agrawal -

The solution you are telling Prashant, is for calculating the extension in the string at equilibrium.

Whereas to calculate max. elongation, just consider all the forces acting on the sphere. Take a differential element for the velocity from 0 to 0. The you will get two solutions. One is zero and the other is the required answer.

Don't get confused with max elongation and elongation in equilibrium.

In reply to pulkit pandey

Re: doubt

by gaurav sharma -
For force method you need to know the max acc as forces are not at equi hence  energy method is easiest  .