Question

In the given figure, find the displacement of the block $A$ in the $x$-axis in the time interval of $3s$ (String is massless and inextensible)

• A. $8m$
• B. $10m$
• C. $12m$
• D. $9m$

Answer 1

The correct option is C $12m$

Due to inextensible nature of string, the end points should have same velocity along the sring

Thus, the velocity of block $A$ i.e. $V_A$ along the string is equal to the velocity of the block $B$ along the string.

So, from the given figure above
$\Rightarrow V_A=V_B=5m/s$
$\therefore$ the velocity of block $A$ along $x$-axis is
$V_{Ax}=5\cos {37}^{\circ }=4m/s$
Hence, displacement in $x$-axis is $V_{Ax}\times t\Rightarrow 4\times 3=12m$