Question

A plank with a box on it at one end is gradually raised about the other end. As the angle of

inclination with the horizontal reaches 30° , the box starts to slip and slides 4.0 m down the

plank in 4.0 s. The coefficients of static and kinetic friction between the box and the plank will
be, respectively ?

#IIT-JAM​​

Answer 1

Static coefficient of friction is μs=tan30o=0.577≈0.6

For kinetic friction,  ma=mgsin30−f=mgsin30−μkmgcos30

                                 a=gsin30−μkgcos30....(1)

and also using S=ut+1/2at2,

                 ⇒4=0+(1/2)a(4)2

               or a=0.5m/s2

Now from (1) we get, 0.5=10(1/2)−μk(10)(23)

or μk=534.5=0.5

refer to this related ans.

it may help to understand ♡

Answer 2

$\textbf{Answer:-}$

Hope it helps you ❤️AKKI❤️