Constant Speed
In vacuum, light travels with a constant speed, c, of:
c=299 792 458m/s
1. It takes light 8.33 min. to travel the distance between the Sun and the moon. Calculate the distance travelled.
2. Astronauts have placed mirrors on the Moon, and hence it is possible to measure the distance to the Moon by sending a laser beam to the Moon: the mirrors reflect the light and send it back to Earth. The distance to the Moon changes during a year, as you can see from the graph below. Use the graph to find the time it would take light to travel from the Earth to the Moon the 1st of February and 1st of August in the shown year.
3. Imagine that you are sitting in an airplane that flies with constant speed from Copenhagen to Berlin. It is 14:10, you are currently 100 km from Copenhagen, and the average speed of a commercial airliner is 885 km/h.
a) How far from Copenhagen will you be at 14:30?
b) When did the plane leave Copenhagen (ignoring the time it takes to accelerate the plane?
c) The distance between Copenhagen and Berlin is 355,7 km. When will you arrive in Berlin?