Question

A $30kg$ block rests on a rough horizontal surface. A force of $200N$ is applied on the block. The block acquires a speed of $4m/s$ , starting from rest in $2s$ . What is the value of coefficient of friction?

• A. $10/3$
• B. $\sqrt{3}/10$
• C. $0.47$
• D. $0.185$

Answer 1

Answer: (C)

$0.47$

The acceleration is given as

$v=u+at$

$a=2m/s^2$

The force applied on the horizontal surface is such that it just overcome the static friction

$F-\mu N=ma$

$200-\mu \cdot 30\cdot 10=30\times 2$

The static friction is$0.47$