A block slides down an inclined surface of inclination 30o with the horizontal Starting (rom rest it covers 8 m in the first two seconds. Find the coefficient of kinetic friction between the two.
Angle of inclination= 30o
Distance travelled (s) = 8m
Time taken (t)= 2 sec
Let us consider the acceleration of the body= a
Initial velocity of the body= 0m/s
Using equation of motion
s=ut + at2
Now, the net force on the body= m.a = m (4)= 4m N
The frictional force experienced by body while moving= f
But, according to the diagram shown, net force on the body is
= mgsin30°-f
= mg-f
Equating the two equations,
= mg-f = 4m
f=0.9 m
Normal force on the body= mgcos30° = (9.8)m= 8.48m
Coefficient of kinetic energy= = 0.11
Hence, coefficient of friction between the surfaces is 0.11