Under the action of load `F_(1),` the length of a string is `L_(1)` and that under `F_(2),` is `L_(2).` The original length of the wire is

Options

A. `[L_(1)F_(1)-L_(2)F_(2)]//[F_(1)+F_(2)]`
B. `[L_(1)F_(2)- L_(2)F_(1)]//[F_(1)-F_(2)]`
C. `[L_(1)F_(2)-L_(2)F_(1)]//[F_(2)-F_(1)]`
D. `[L_(1)F_(2)-L_(2)F_(1)]//[F_(1)+F_(2)]`

Answer

C

Explanation

`L=(L_(1)T_(2)-L_(2)T_(1))/(T_(2)-T_(1))=(L_(1)F_(2)-L_(2)F(1))/((F_(2)-F_(1))).`