Question

Find acceleration of block $A$ and $B$. If ${\mu }_1=0.8$ and ${\mu }_2=0.4$

• A. $0m/s^2$ and $0m/s^2$
• B. $1m/s^2$ and $1/2m/s^2$
• C. $2m/s^2$ and $0m/s^2$
• D. $1/2m/s^2$ and $1/4m/s^2$

Answer 1

Answer: (C)

Limiting friction between $B$ and ground
$=0.4(5+10)(10)=60N$
$\Rightarrow$ acceleration of $B$ is zero.
acceleration of block $A$.
$a_A=\frac{50-0.8(5)(10)}{5}=2m/s^2$
In this case lower block can not move at all.