Awoman on the rear platform of a train moving with constant velocity drops a coin while leaning over the rail. describe the path of the coin as seen by (a) the woman on the train, (b) a person standing on the ground near the track, and (c) a person in a second train moving in the opposite direction to the first train on a parallel track.

1) Straight line path

2) Parabolic Path

3) Parabolic path

Explanation:

Part a)

When coin is observed by the woman who is on the train then she will observe the path of the coin to be a straight line path

It is because the motion of the coin in horizontal direction in the direction of the motion of train will be same as that of woman.

so in that direction coin will not appear to move while in vertical direction it will freely fall.

Part b)

A person is standing on ground will observe the path to be a parabolic path because he will see the coin to be moving in the direction of train motion with uniform speed and simultaneously it will move vertically downwards with uniform acceleration.

Part c)

A person in train which is moving in opposite direction with same speed will also observe the coin in parabolic path because he will see the coin to be moving with double the speed in horizontal direction while in vertical direction the coin will appear in free fall

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.