# Determine the speed of a spacecraft that flew in polar orbit at an altitude of 100 km above the ground and covered

Determine the speed of a spacecraft that flew in polar orbit at an altitude of 100 km above the ground and covered the distance between the tropics in 15 minutes. 1) Average radius of the Earth = 6371 km.
6371 km + 100 km = 3471 km is the radius of the spacecraft flight path at an altitude of 100 km.
2) L = 2 πr = 2 × 3.14 × 3471 = 40637 km is the orbit length.
3) 40637 km: 360о = 112.88 km – the length of 1о arc at this height.
4) 23.5о + 23.5о = 47о – the distance between the tropics in degrees.
5) 47о × 112.88 km = 5305.36 km – the distance between the tropics in kilometers.
6) 5305.36 km: 900 s = 5.89 km / s – the speed of the spacecraft. Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.