Abike rider pedals with constant acceleration to reach a velocity of 7.8 m/s over a time of 4.2 s. during the period of acceleration, the bike's displacement is 19 m. what was the initial velocity of the bike?

To calculate the initial velocity of the bike, we use the following equation

.

or

Here, u is initial velocity, v is final velocity, t is the time and d is the distance covered by bike.

Given, , and .

Substituting these values in above equation, we get

.

Thus, the initial velocity of the bike is 1.2 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.