Question

In the figure below, if all the surfaces are assumed to be smooth and the force $F=100N$. If the acceleration of block $B$ of mass $20kg$ is $a$ and tension in string connecting block $A$ of mass $20kg$ is $T$ then, just after force $F$ is applied find the values of $T$ and $a$.

• A. $T=0,$ and $a=5m/s^2$
• B. $T=100N,$ and $a=0$
• C. $T=200N,$ and $a=5m/s^2$
• D. $T=100N,$ and $a=5m/s^2$

Answer 1

The correct option is A $T=0,$ and $a=5m/s^2$

As there is no unbalanced force acting on block $A$, tension in the string will be zero.
$⟹T=0N$
$F=m_B.a$

$a=\frac{F}{m_B}=\frac{100}{20}=5m/s^2$