Question

A person, exerting a steady force of $200N$, pushes a box of mass $50kg$ across a flat wooden floor. If the box does not move while he pushes. Find out the coefficient of kinetic friction between the box and the floor?

• A. $0.2$
• B. $0.4$
• C. $0.5$
• D. $0.6$
• E. $0.8$

Answer 1

Answer: (B)

$0.4$

The equation of motion of the box, $ma=F-f=F-\mu N$

As box does not move so $a=0$ so $F=\mu N=\mu mg$

or $\mu =\frac{F}{mg}=\frac{200}{50\left(10\right)}=0.4$