A force of 200 N is exerted on an object of mass 40 kg. What is the
acceleration?

The acceleration is 5 m/s2.

Explanation:

We calculate the acceleration, with the data of mass and force, through the formula:

F= m x a ---> a= F/m

a= 200 N/40 kg        1N= 1 kg x m/s2

a= 200 kg x m/s2/ 40 kg

a= 5 m/s2

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.