Question

Two very small charged spheres of
charges Q1 and Q2 and of masses
My and M2 are kept on the surface of a
smooth table. Find the magnitude of
relative acceleration of My with respect
to M2 when separation between their
centres is r (consider effect of electric
for.ce only)​

Answer 1

Explanation:

The gravitational force between the two masses is given as −

r

2

GM

1

M

2

and the electric force between them is given as

4πϵ

0

1

r

2

Q

1

Q

2

.

For the masses to remain stationary under these two forces, the net force on each must be zero.

Thus −

r

2

GM

1

M

2

+

4πϵ

0

1

r

2

Q

1

Q

2

=0

⟹Q

1

Q

2

>0

Thus they must have same sign.