How to find the first cosmic velocity
In aerospace science,first cosmic velocityIt refers to the minimum speed required for an object to move in a uniform circle around the earth near the earth's surface. It is one of the basic conditions for breaking away from the gravitational constraints of the earth and entering space. This article will explain in detail the calculation method of the first cosmic velocity, and combine it with the hot topics on the Internet in the past 10 days to help readers better understand this concept.
1. Definition of the first cosmic velocity
The first cosmic speed (also known as orbiting speed) refers to the minimum speed required for an object to move in a uniform circular motion around the earth near the earth's surface, using the earth's gravity as the centripetal force. Its theoretical value is7.9 kilometers/second.
2. Calculation formula of the first cosmic velocity
According to Newtonian mechanics and the law of universal gravitation, the derivation formula of the first cosmic velocity is as follows:
| formula | Description |
|---|---|
| v = √(GM/R) | G is the gravitational constant, M is the mass of the earth, and R is the radius of the earth. |
| v ≈ 7.9 km/s | Approximate value after substituting earth parameters |
3. Detailed explanation of calculation steps
1.Gravity provides centripetal force: When an object moves around the earth, the earth's gravitational pull on the object acts as a centripetal force.
2.Formula derivation: According to the combination of the centripetal force formula and the universal gravitation formula, the expression of the first cosmic velocity can be obtained.
| physical quantity | numerical value | unit |
|---|---|---|
| The universal gravitational constant G | 6.67430×10⁻¹¹ | N·m²/kg² |
| Earth mass M | 5.972×10²⁴ | kg |
| Earth radius R | 6.371×10⁶ | m |
3.Substitute calculation: Substituting the above values into the formula, the theoretical value of the first cosmic velocity can be obtained.
4. Association of hot topics on the entire network in the past 10 days
Recent hot topics in the aerospace field include:
| topic | heat index | Related points |
|---|---|---|
| SpaceX Starship latest test flight | 9.2/10 | Demonstrated practical application of first cosmic velocity |
| New mission of China Space Station | 8.7/10 | Need to accurately calculate spacecraft speed |
| NASA moon base plan | 8.5/10 | Involving the calculation of the speed of the second universe |
5. Frequently Asked Questions
Q: Why is the first cosmic speed 7.9km/s?
A: This is a theoretical value calculated based on the mass and radius of the Earth to ensure that the spacecraft can overcome the Earth's gravity without falling.
Q: Will altitude changes affect the first cosmic velocity?
A: Yes. As altitude increases, the required first cosmic velocity decreases because Earth's gravity weakens.
6. Practical application examples
| spacecraft | Launch speed | Remarks |
|---|---|---|
| international space station | About 7.7km/s | Slightly lower than the theoretical value due to its orbital height |
| Beidou navigation satellite | About 7.8km/s | Medium Earth orbit requires higher speeds |
7. Summary
The calculation of the first cosmic velocity is the basic knowledge of aerospace engineering, and understanding its principles is crucial to understanding modern aerospace technology. By mastering the law of universal gravitation and the law of circular motion, we can accurately calculate the first cosmic velocity on the surfaces of different celestial bodies. The recent boom in global space activities has highlighted the importance of this basic theory.
With the advancement of aerospace technology, human beings' ability to control the speed of the universe is also constantly improving. From the first cosmic speed to the second and third cosmic speeds, each level of breakthrough represents a new milestone in human exploration of space.
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