The speed of light is equal to 300000 km/s.
Let's find how many seconds there are in a year:
1 year = 365 days = 365 * 24 hours = 365 * 24 * 60 minutes = 365 * 24 * 60 * 60 seconds
Now, multiplying this amount of time by the speed of light, we have the distance traveled by the light in one year:
distance = speed * time
distance = 300000 * 365 * 24 * 60 * 60
distance = 9,460,800,000,000 km
Now, the time needed for a distance of 10 km is:
distance = speed * time
10 = 300000 * time
time = 10/300000
time = 3.33 * 10^-5 seconds
The speed of sound is about 1225 km/h.
So, for a distance of 10 km, we have:
10 = 1225 * t
t = 10/1225
t = 0.008163265 hours
t = 29.39 seconds
The distance from moon to Earth is 384,400 km, so the time needed is:
384400 = 300000 * t
t = 384400/300000
t = 1.2813 seconds
