Question

There are two identical springs each of spring constant k. Here springs, pulley and rods are massless and block has mass m. What is the extension of each spring at equilibrium ?

• A. $\frac{mg}{k}$
• B. $\frac{2mg}{k}$
• C. $\frac{mg}{2k}$
• D. $\frac{3mg}{4k}$

Answer 1

Answer: (A)

$\frac{mg}{k}$

Answer 2

Draw a free body diagram of above figure

FBD of lower rod

$k x+k x =2 \,m g$
$\Rightarrow \, x =\frac{m g}{k}$