Question

The distance of the moon to the Earth is 384,400 km.
The speed of light is 2.998 x 108 m/s.
Work out how long it will take light to travel from the moon to the Earth.
Include suitable units.

Answer 1

Answer: 1.3 seconds

Step-by-step explanation:

Given: Distance of the moon to the Earth = 384,400 km = 384400 x 1000 meters = 384400000 meters.  [1 km = 1000 m]

Speed of light =$2.998 \times 10^8$  m/s = 299800000 m/s

Formula: $\text{Time}=\dfrac{\text{Distance}}{\text{Speed}}$

Let t be the time taken by the light to travel from the moon to the Earth.

$t=\dfrac{384400000}{299800000}\approx1.3\text{ seconds}$

Hence, it will take approximately 1.3 seconds for the light to travel from the moon to the Earth.