Question

Find acceleration of block $\text{B}$ if $F=40\text{N}$.
(Take $g=10{\text{m/s}}^2$)

• A. $3{\text{m/s}}^2$
• B. $0$
• C. $5{\text{m/s}}^2$
• D. $6{\text{m/s}}^2$

Answer 1

The correct option is B $0$

FBD of block $\text{A}:$


$f_1={\mu }_{1}N=0.5\times 50=25\text{N}$

As $F>f_1$, block $\text{A}$ will accelerate with some acceleration.

FBD of block $\text{B}:$


From FBD,

$f_2=\mu (m_1+m_1)g=0.2\times 150=30\text{N}$

As $f_2>f_1$, block $\text{B}$ will not move.

So, acceleration of block $\text{B}$ will be zero.

Hence, option $\left(b\right)$ is correct.