Question

The co-efficient of friction between two surfaces is $\mu =0.8$. The tension in the string as shown in the figure is

• A. $0N$
• B. $6N$
• C. $4N$
• D. $8N$

Answer 1

The correct option is A $0N$

Maximum frictional force acting on the block $f=\mu mg\cos {30}^o$

$f=0.8\times 1\times 9.8\times 0.866=6.8N$

Downward force $=mg\sin 30=1\times 9.8\times 0.5=4.9N$

Since downward force is less than maximum frictional force, thus the tension in the string is zero.