Question

Two blocks are connected by a string as shown in the diagram. The upper block is hung by another string. A force $F$ applied on the upper string produces an acceleration of $2{\text{m/s}}^2$ in the upward direction in both the blocks. If $T$ and $T^{\prime }$ be the tensions in the two parts of the string, then (take $g=10{\text{m/s}}^2$ )

• A. $T=72\text{N}$ and $T^{\prime }=48\text{N}$
• B. $T=48\text{N}$ and $T^{\prime }=72\text{N}$
• C. $T=48\text{N}$ and $T^{\prime }=24\text{N}$
• D. $T=24\text{N}$ and $T^{\prime }=48\text{N}$

Answer 1

The correct option is A $T=72\text{N}$ and $T^{\prime }=48\text{N}$

As same string $F=T$
FBD of $4\text{Kg}$ block
$T^{\prime }-4g=4a$
$T^{\prime }=4g+8$
$T^{\prime }=48\text{N}$




FBD of $2\text{kg}$ block.
$T-T^{\prime }-2g=2a$
$T=2(10+2)+T^{\prime }$
$T=24+48$
$T=72\text{N}$