One observer stands on a train moving at a constant speed, and one observer stands at rest on the ground. The person on the train stands at the back of the car and turns on a flashlight; the light travels to the front of the car, bounces off a mirror, and returns to the back of the car (assume the light is traveling in a vacuum). The observer on the ground measures the time it takes for the light to take this path and knowing the length of the car, calculates the speed of light. What value does she obtain?

a.)greater than c

b.) equal to c

c.) less than c

d.) value cannot be calculated without knowing the speed of the train

Option D.

Value cannot be calculated without knowing the speed of the train

Explanation:

The speed of the beam can only be calculated accurately when the speed of the train is put into consideration. Based of the theory of relativity, the observer is on the ground, and the train is moving with the beam of light inside it. This causes a variation in the reference frames when making judgements of the speed of the beam. The speed of the beam will be more accurate if the observer is moving at the same sped of the train, or the train is stationary.

To get the correct answer, we have to subtract the speed of the train from the speed calculated.

when heated, the valance electrons increased their speed and transferred the heat from electron to electron.   i just took the test.

continuous conducting path for current, power supply