Engineers approximate the elliptical orbit of Earth and Mars with a circular orbit. This is not a bad approximation because the eccentricity of both orbits is very low making them very close to being circular. Any object orbiting in a circular path will have an average orbital speed equal to the distance traveled divided by the time it took to travel that distance. The distance traveled in completing one circular orbit is the circumference of the circle, 2πR. The time it takes to complete one orbital revolution is called the period, T. So the equation for orbital speed becomes:   v= distance/ time v= (2πr)/T WHERE: v = orbital speed in km/hour r = radius of the circle, distance from the planet to the sun in kilometers T = period of time for one revolution in hours Important quantity: use π = 3.1416     

Question 1. The Earth is 150 million km from the sun. It completes one orbit in approximately 365.25 days. Calculate the orbital speed of Earth in km/hour.

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Answer Time period of Angulor vel el of Dist g ... View the full answer