Atrain traveling at 7.55m/s accelerates to a distance of 975m in 31.5 s. whats the final velocity of the train?
a)227m/s
b)54.4
c)7.61
d)69.5

B. 54.4  m/s

Explanation:

Using the equation;

S = ut + 1/2at²

Where;

v is the final velocity

u is the initial velocity,

a is the acceleration,

s is the displacement

Therefore;

975 =(7.55×31.5) + (0.5×a× 31.5²)

975 = 237.825 + 496.125a

496.125a = 737.175

a = 1.486 m/s²

But;

v = u + at

  = 7.55 m/s + (1.486 × 31.5)

   = 54.355 m/s

   = 54.4 m/s

Therefore;

The final velocity is 54.4 m/s

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.