The lengths of smooth & rough inclined planes of 450 inclination is same. Times of sliding of a body on two surfaces is t1, t2 and μ = 0.5, then t1:t2=
2 :1
2:3
1:2
3:2
t1t2=2lgsinθg(sinθ−μKcosθ)2ℓ
=sinθ−μKcosθsinθ=1−μKcotθ
=1−0.5=12