Question

Find the reading of the spring balance if it is assumed to be of negligible mass.
(Take $g=10m/s^2$)

• A. $3kg$
• B. $2kg$
• C. $2.5kg$
• D. $2.4kg$

Answer 1

The correct option is D $2.4kg$


For the whole system, acceleration is
$a=\frac{3g-2g}{5}=\frac{g}{5}$


For $3kg$ body,

$3g-T=3a$
$T=3(g-a)=3\times \frac{4g}{5}=\frac{12\times 10}{5}=24N$
Hence, the reading will be $=\frac{24}{10}=2.4kg$