An old streetcar rounds a flat corner of radius 6.80 m, at 18.0 km/h. What angle with the vertical will be made by the loosely hanging hand straps?

Explanation:

Given data

Radius R=6.80 m

Velocity v=18 km/h =5 m/s

First we need to set up for Force in vertical (y) and horizontal (x)

∑Fy=0=TCosα-W

∑Fx=ma=Fc=TSinα

Solve Vertical force equation for T,substituting mg for W

Substitute expression for Fc and T into horizontal force and simplify it we get

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.