Answer:
Explanation:
Acceleration without friction on an inclined plane = g sinθ
Acceleration with friction on inclined plane = g sinθ - μ g cosθ
s = 1/2 a t²
For motion on friction-less surface
s = 1/2 g sinθ t₁²
For motion on frictional surface
s = 1/2( g sinθ - μ g cosθ) t₂²
t₂ = 2t₁
( sinθ - μ cosθ) t₂² = sinθ t₁²
( sinθ - μ cosθ) 4t₁² = sinθ t₁²
( sinθ - μ cosθ) 4 = sinθ
4sinθ - sinθ = 4μ cosθ
3sinθ = 4μ cosθ
3 / 4 tanθ =μ
μ = .75 tanθ