Question

A $1 \,kg$ block '$B$' rests as shown on a bracket '$A$' of same mass. Constant forces $F_1=20 \,N$ and $F_2=8\, N$ start to act at time $t=0$ when the distance of block $B$ from pulley is $50\, cm$. Time (in sec) when block $B$ reaches the pulley is $t$. Find the value of $10 t$.

Answer 1

First find out acceleration of A so for this
$\Rightarrow a=20-2F_{2}=20-2\times 8$
$a_{A}=4\,m / s^{2}$
Now use pseudo concept (in which A is non inertial frame)


$\Rightarrow 8-4=4\,m / s^{2}$
Now $\frac{50}{100}=\frac{1}{2}\times 4\times t^{2}$
$t=\frac{1}{2}=0.5 \, sec$
$\Rightarrow \, 10t=5$