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Circular Orbits. Kevin Driscoll Adam Kelly. The speed of objects in circular orbit are unchanged by gravity. Travels in a similar motion in relation to a bowling bowl rolling along a bowling alley Why? Gravity does not pull forward or backward
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Circular Orbits Kevin Driscoll Adam Kelly
The speed of objects in circular orbit are unchanged by gravity. • Travels in a similar motion in relation to a bowling bowl rolling along a bowling alley • Why? • Gravity does not pull forward or backward • It pulls straight downward, perpendicular to the ball’s motion. Circular Orbits
If an object moved in the direction of gravity, its speed would increase • If an object moved against the direction of gravity, its speed would decrease • It moves at a constant speed perpendicular to the force of gravity Circular Orbits
The average satellite’s period is about 90 minutes. • Period- the time of a complete orbit • In higher altitudes, the orbital speed is less and the period is longer • To calculate orbital speed: • G=Universal Gravity, M=mass of the earth, r=altitude of the object Circular Orbits
Isaac Newton calculated… • An object in circular orbit close to Earth moves at 8 km/s • Was not considered because this speed was impossible at that point of time Circular Orbits
Why doesn’t gravitational force change the speed of a satellite in circular orbit? • The satellite does not travel in or against the force of gravity. It moves perpendicular to the force so speed remains constant. Circular Orbits