In order to determine the necessary average speed to cover the next 220 km in a span of 9 hours, we use the formula: speed = distance/ time. The given values are the distance = 220 km and time = 9 hours. Thus, the speed can be solved by dividing 220 km by 9 hours. We then obtain the average speed needed to be 24.44 km/h.
If the observer on Earth measures the speed of the spacecraft
as 0.700c and its length as 78.0 meters, then engineers aboard
the spacecraft measure their vehicle as 142.4 meters long.
They're both correct. There's no such thing as the spacecraft's
"real" or "proper" length.