Answer:1.71 m/s
Explanation:
Given
mass of Susan 
Inclination 
Tension 
coefficient of Friction 
Resolving Forces Along x axis

where

since there is no movement in Y direction therefore

and 
Thus 


Work done by applied Force is equal to change to kinetic Energy




Answer:
Explanation:
separation between two gaps, d = 5 cm
angle between central and second order maxima, θ = 0.52°
use
d Sinθ = n λ
n = 2
0.05 x Sin 0.52° = 2 x λ
λ = 2.27 x 10^-4 m
λ = 226.9 micro metre