A block with a mass of 3 kg starts from rest at the top of a 24.5 degree incline and slides 2 m down the incline in 1.35 s.

The distance moved by a body in t seconds that starts with a velocity u an travels under an acceleration a is given by D = u*t + (1/2)a*t^2

In the problem the slope of the incline is 24.5 degrees. This gives the component of acceleration due to gravity along the incline as g*sin 24.5. The deceleration due to friction is equal to 3*9.8*cos 24.5*C/3 = cos 24.5*9.8*C where C is the coefficient of kinetic friction. This gives:

2 = 0*1.35 + (1/2)*(9.8*sin 24.5 - cos 24.5*9.8*C)*1.35^2

=> 4/(1.35^2) = (9.8*sin 24.5 - cos 24.5*9.8*C)

=> cos 24.5*9.8*C = (9.8*sin 24.5 - 4/1.35^2)

=> (4/1.35^2 - 9.8*sin 24.5)/9.8*cos 24.5

=> C = 0.2096

The coefficient of kinetic friction is 0.2096