Satellite Motion Monika V Sikand Ph.d Student Stevens Institute of Technology Department of Physics. Light and Life Laboratory. Hoboken.

OBJECTIVE Review laws of motion and gravitation Satellite motion Escape velocity Geosynchronous orbit(Telecommunication satellites)

Newton’s laws of motion I. Law of Inertia II. F=ma III. Action-Reaction Isaac Newton January 4, March31,1727

What is Gravity?

Gravity is a pulling force It pulls things down towards the earth

Things fall because of gravity

Things always fall down

Why do people not fall off the earth?

Newton’s Law of Gravitation

Gravity holds everything and every one on the earth

In Space, Gravity keeps the planets moving around the sun

Gravity on earth and moon

So how can we understand orbital motion?

Motion of the ball on earth

Example

Earth’s curvature

Satellite Smaller body revolving around a larger body

Natural satellites Moon, planets, comet

Artificial satellites Weather, spy, communication

Escape velocity Artificial satellite in a circular orbit around earth first achieving a speed of 7900m/s. If speed greater than 7900m/s satellite has a elliptical orbit. If velocity greater than 11km/s then satellite leaves earth’s orbit and has a escape orbit. The escape orbit’s velocity is called escape velocity.

Figure 7-22 Satellite orbits

Geostationary Earth Orbit (GEO)  Orbit is synchronous with the earths rotation.  From the ground the satellite appears fixed.  Altitude is about 22,300 miles or 36,000Km.  Coverage to 40% of planet per satellite.

Conclusion Newton’s law of gravitation F =Gm 1 m 2 /r 2 Satellites are revolving bodies around earth. Escape velocity is the maximum velocity required to escape the earth’s orbit. Geostationary orbits are synchronized with earth’s rotation at km of height.