Question

For the arrangement as shown in the figure, the maximum force F, for no relative motion between block is

• A. 12 N
• B. 8 N
• C. 20 N
• D. 24 N

Answer 1

The correct option is D

24 N

To start motion F > 8 M

Acceleration $=\frac{F-8}{8}$

$\frac{F}{2}-f_r=3\left(\frac{F-8}{8}\right)\Rightarrow \frac{F}{8}+3=f_r$
$\frac{F_{max}}{8}+3=f_{Lm}=6N\Rightarrow F_{max}=24N$