Mars is 230 million km from the sun. It completes one orbit in a period of approximately 687 days. Calculate the orbital speed of Mars in km/hour. (Note: a Mars day is 24.6597 hours) Use the equations that appear below to answer the question.

To solve questions of this nature, 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 planet to sun in kilometers T = period or time for one revolution in hours Important quantity: use π = 3.1416