As an expert in the field of aerospace engineering, I'm thrilled to discuss the fascinating topic of rocket launches. The speed at which a rocket must travel to launch into space is a critical aspect of spaceflight. The velocity needed for a rocket to achieve a stable orbit around the Earth is known as the first cosmic velocity, or more specifically, the circular orbital velocity. This is approximately 7.9 kilometers per second, which is indeed over 20 times the speed of sound.

To understand why this speed is necessary, we must delve into the principles of orbital mechanics. The Earth's gravity is a force that acts upon all objects near its surface, and to overcome this force and achieve orbit, a rocket must reach a certain speed. This speed is derived from the balance between the gravitational force pulling the rocket back towards Earth and the centrifugal force pushing it outward due to its motion.

The formula for orbital velocity \( v \) can be expressed as:
\[ v = \sqrt{\frac{GM}{r}} \]
where \( G \) is the gravitational constant, \( M \) is the mass of the Earth, and \( r \) is the radius of the orbit. For a low Earth orbit (LEO), which is approximately 200 kilometers above the Earth's surface, the orbital velocity is very close to the first cosmic velocity mentioned earlier.

The process of reaching this speed involves a multi-stage rocket, where each stage is designed to accelerate the rocket to a certain point before detaching, reducing the mass and allowing the remaining stages to accelerate more efficiently. The initial stages of a rocket launch are the most energetically demanding, as the rocket must overcome both gravity and atmospheric drag.

Once the rocket has cleared the densest part of the atmosphere, it continues to accelerate into space. The final stage of the rocket then places the payload into the desired orbit. This entire process, from ignition to reaching the required orbital velocity, can take anywhere from a few minutes to over half an hour, depending on the specific rocket and its mission profile.

It's important to note that the 7.9 kilometers per second is the speed needed for a circular orbit at the Earth's surface. For higher orbits, such as geostationary orbit, the required speed is less because the centrifugal force is balanced against a weaker gravitational pull due to the increased distance from the Earth's center.

In conclusion, the speed of a rocket launch into space is a complex interplay of physics, engineering, and mission objectives. The 7.9 kilometers per second threshold is a fundamental milestone that every launch must surpass to achieve orbit and explore the cosmos beyond our planet.

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If a rocket is launched from the surface of the Earth, it needs to reach a speed of at least 7.9 kilometers per second (4.9 miles per second) in order to reach space. This speed of 7.9 kilometers per second is known as the orbital velocity, it corresponds to more than 20 times the speed of sound.read more >>