Which best describes the forces identified by newton’s third law of motion? equal and acting on different objectsequal and acting on the same objectunequal and acting on different objectsunequal and acting on the same object

Newton's third law is identified by forces are equal and acting on different objects.

Explanation :

Newton's third law states that for action there is an equal and opposite reaction. The action and reaction act on different objects.  

For example,

In the attached figure the person is coming out of the boat. It is observed that the boat moves slightly in the backward direction when he moves forward. The action force is acting on the man and the reaction force is acting on the boat.

So, the two forces are acting in the opposite direction.  

Hence, the correct option is (A) " equal and acting on different objects "

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.