How Fast Is 103 Km

In space, gravity supplies the centripetal force that causes satellites (like the moon) to orbit larger bodies (like the Earth). Thanks to physics, if yous know the mass and altitude of a satellite in orbit around the Earth, you can calculate how rapidly it needs to travel to maintain that orbit.

A item satellite tin have only ane speed when in orbit effectually a particular torso at a given distance because the force of gravity doesn't change. So what's that speed? You tin calculate it with the equations for centripetal force and gravitational force. For a satellite of a particular mass, grand ₁, to orbit, you need a corresponding centripetal forcefulness:

This centripetal force has to come from the force of gravity, and so

Y'all can rearrange this equation to get the speed:

This equation represents the speed that a satellite at a given radius must travel in lodge to orbit if the orbit is due to gravity. The speed can't vary as long as the satellite has a constant orbital radius — that is, as long every bit information technology'southward going around in circles. This equation holds for any orbiting object where the attraction is the force of gravity, whether it'due south a man-fabricated satellite orbiting the Earth or the Earth orbiting the sun. If you desire to notice the speed for satellites that orbit the World, for example, yous use the mass of the Earth in the equation:

Hither are a few details yous should annotation on reviewing the orbiting speed equation:

• Y'all have to apply the distance from the center of the Earth, not the distance in a higher place Globe's surface, as the radius. Therefore, the distance y'all use in the equation is the altitude between the two orbiting bodies. In this instance, y'all add the distance from the center of the Earth to the surface of the Globe, six.38 × 10⁶ meters, to the satellite's pinnacle to a higher place the World.

• The equation assumes that the satellite is loftier enough off the ground that information technology orbits out of the atmosphere. That assumption isn't really truthful for artificial satellites; even at 400 miles above the surface of the Earth, satellites practice feel air friction. Gradually, the elevate of friction brings them lower and lower, and when they hitting the temper, they burn upwardly on re-entry. When a satellite is less than 100 miles in a higher place the surface, its orbit decays appreciably each time it circles the Earth. (Await out beneath!)

• The equation is independent of mass. If the moon rather than the bogus satellite orbited at 400 miles and you could ignore air friction and collisions with the Earth, it would take to get at the same speed as the satellite in society to preserve its close orbit (which would brand for some pretty spectacular moonrises).

Human being-made satellites typically orbit at heights of 400 miles from the surface of the Earth (about 640 kilometers, or 6.4 × 10^five meters). What's the speed of such a satellite? All you have to exercise is put in the numbers:

This converts to about sixteen,800 miles per hour.

Virtually This Article

This commodity is from the book:

• Physics I For Dummies ,

About the book author:

Dr. Steven Holzner has written more than 40 books about physics and programming. He was a contributing editor at PC Mag and was on the faculty at both MIT and Cornell. He has authored Dummies titles including Physics For Dummies and Physics Essentials For Dummies. Dr. Holzner received his PhD at Cornell.

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• Physics ,

How Fast Is 103 Km,

Source: https://www.dummies.com/article/academics-the-arts/science/physics/how-to-calculate-a-satellites-speed-around-the-earth-174067/

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