Question

A uniform rod of length L , area of cross-section A , mass m and Young 's modulus Y is pulled on horizontal surface by a force f , such that the friction acting on it is F/2 . What if the elongation in the rod?

• A. $\frac{FL}{2AY}$
• B. $\frac{FL}{AY}$
• C. $\frac{3FL}{2AY}$
• D. $\frac{3FL}{4AY}$

Answer 1

The correct option is A $\frac{FL}{2AY}$

$\begin{array}{c}\text{Since rod is not moving Tension in rod is frictional}\\ \text{force}F/2\end{array}$

$\begin{array}{cc}\text{elongation}\Delta l=& \frac{\left(F/2\right)l}{AY}\\ \Delta l& =\frac{Fl}{2AY}\end{array}$