How Do Rockets Overcome The Earth’s Gravity?

Do you know which was the first rocket to be launched into space?

 If you said Sputnik 1, then you are partially correct. In 1942, Germany tested and launched the V2 Missile which went high enough to reach space. Then on October 4th, 1957, the Sputnik was launched on top of an R7 Intercontinental ballistic missile by the Soviet Union.

 

What is a rocket actually?

In simple words, it is a closed chamber, filled with fuel, and at one end of the chamber, a small nozzle is present. At this nozzle, the fuel is burnt and hot gasses at high pressure are forced out of the chamber. As per Newton’s third law, “Every action has an equal and opposite reaction.” The chamber or let’s rather call it the rocket, moves in the opposite direction of the forced outgasses.

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Rocket

Thus it does not have to overcome the forces of Earth’s gravity. On the other hand, rockets for the most part of their journey have to move vertically to reach space. This brings a lot of implications to its engineering of it. Before a rocket escapes into space, it needs to achieve a pretty high speed, also known as the escape speed or escape velocity. Physicists have calculated this value to be 11.2 kilometers per second, which is almost 33 times the speed of sound. Reaching escape velocity would mean that the force at which the rocket is being pushed towards space is more than or equal to the force of gravity by which the rocket is being pulled down to Earth.

Coming back to the example of the car. A car would need less fuel to travel a distance on the surface of the earth whereas a rocket would require fuel of weight more than the weight of the rocket components themselves. Modern-day rockets are almost 85% fuel and 15% payload and launch vehicle structures.

Lift Off!

Gravity is not the only force pulling the rocket towards its annihilation on the ground. When the rocket travels at such a high speed, it experiences drag which is the atmosphere trying to push down on the rocket. Same principle, Newton’s third law. When the rocket is moving up, it is pushing the atmosphere as well.

The particles in the atmosphere apply an equal and opposite force. The cost of launching a rocket into space is a pretty huge amount. Scientists found out that the speed of rotation of the earth is pretty high at the equator. Hence rockets launched at the equator would require less fuel to reach space. Pretty cool right?.

So now you know, what it takes to overcome the forces of gravity. It’s basically a lot of fuel, some intelligent thinking, and a lot of math.

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