Which of the following has different dimensional formula ?

Options

A. Force constant
B. surface tension
C. surface energy
D. torque

Answer

`1.8xx10^(5) sec`

Explanation

`U_(initial")=(KQ^(2))/axx2=(2KQ^(2))/a`
`U_("final")=(KQ^(2))/((a/2))xx2=(4KQ^(2))/a`
`DeltaU=(2KQ^(2))/a=1.8xx10^(8)J=P prop t`
`t=(1.8xx10^(8))/10^(3) sec=1.8xx10^(5)` sec