| [Member (365WT)]answers [Chinese ] | Time :2019-11-11 | The speed of the first universe refers to the speed at which the object moves around the earth at a uniform circular motion called the first cosmic velocity.
The first cosmic speed is another name: the minimum launch speed of the spacecraft, the maximum operating speed of the spacecraft, and the surrounding speed.
In some questions, when a spacecraft is operating at the first cosmic speed, the spacecraft is operating along the surface of the earth. According to the mechanics theory, v1 = 7.9 km / s can be calculated. In fact, there is a dense atmosphere on the surface of the earth. It is impossible for the spacecraft to move close to the surface of the earth for circular motion. It must be at a flying height of 150 kilometers to make a circular motion around the earth. The spacecraft operates at altitudes of more than a few hundred kilometers from the surface of the ground. The ground-based gravitational force of the spacecraft is smaller than that of the ground, so its speed is also slightly less than v1. The surround speed at this height is 7.8 km/sec.
Derived formula
F=GMm/r2=mv2/r
GM=gr2
Solution v=gr
Substituting R = 6.37 × 10 m, g = 9.8 m / s2, and squared
v= 7.9 km/s |
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