Question

A dynamometer $D$, is connected with two bodies of mass $M=6kg$ and $m=4kg$. If two forces $F=20N$ & $F=10N$ are applied on masses according to figure then reading of the dynamometer will be:

• A. $10N$
• B. $20N$
• C. $6N$
• D. $14N$

Answer 1

Answer: (D)

$14N$

acceleration of the system
$a=\frac{20-10}{6+4}=1m/s^2$

If tension in the spring is $T$ then for $6kg$ block
$20-T=6\times 1\Rightarrow T=14N$
so reading will be $14N$