Answer:
Time,t=2.03seconds
Explanation:
Fg= 4.80×9.80= 47.04N
Maximum accelerating force= 75-47.04=27.96N
F= ma
27.96= 4.80 ×a
27.96/4.80=a
5.825m/s^2 =a
d=1/2at^2
d=12.0m
12=1/2 × 5.825 ×t^2
12 =2.913×t^2
t^2= 12/2.913
t= sqrt(4.120)
t= 2.03seconds
Snell's law: n1Sinα=n2Sin β where α=Incidence angle, β=angle of refraction, n1 and n2 are the indices of refraction for water and air respectively.
Therefore,
Sinα=n2/n1 Sinβ For refracted ray to be along the surface of water, β=90° and thus Sinβ = 1
Sinα=n2/n1= 1/1.33 = 0.7519 => α=sin^-1 (0.7519) = 48.75°
When light moves from a medium of higher index of refraction (such as water) to medium of lesser index of refraction (such as air), the refracted ray is bend such that α is bigger than β. This is internal refraction. At some value of α, β approaches 90°. This incidence angle is called critical incidence angle. Therefore, the current scenario is shows critical angle of incidence.
