Question

A dynamometer $D$ (a force meter) is attached to two masses $M=10kg$ and $m=1kg$. Forces $F=2kgf$ and $f=1kgf$ are applied to the masses. Find out in which of the case gives maximum reading.
(A) $F$ is applied to $M$ and $f$ to $m$.
(B) $F$ is applied to $m$ and $F$ to $M$.
(C) If $M=m=5kg$.(Ignore $m,M$ values in the problem).
(D) If $M$ is doubled to $m$. (Ignore $n,M$ values in the problem).

• A. $A$
• B. $B$
• C. $C$
• D. $D$

Answer 1

The correct option is B $B$

$A)$ When $F$ is applied to $M$ and $F$ to $m$

$=\frac{20-10}{11}=\frac{10}{11}$

$\therefore R-10=\frac{10}{11}$

$\Rightarrow R=10+\frac{10}{11}=\frac{120}{11}N$

$B)$When $F$ is applied to $m$ and $F$ is to $M$

$a=\frac{10}{11}$

$20-R=\frac{10}{11}$

$\Rightarrow R=20-\frac{10}{11}$

$\Rightarrow R=\frac{210}{11}N$

$C)$When $M=m=5kg$

$a=\frac{20-10}{10}=1m/s^2$

$20-R=5\left(1\right)$

$\Rightarrow R=15N$

$D)$ When $M$ is doubled to $m$

$a=\frac{20-10}{3m}=\frac{10}{3m}$

$20-R=m\left(\frac{10}{3m}\right)$

$\Rightarrow R=20-\frac{10}{3}=\frac{50}{3}N$