Author:
Joyce Buda

Mass of Saturn Activity (Project 2)Brief Overview of Activity: Using a modified version of Kepler's thirdlaw, and orbital data from one of Saturn's moons, the mass of Saturncan be determined.Required Items: a calculator, your textbook, pencil & paper.Procedure:You have learned that Kepler's third law, P2 = a3, applies to any objectorbiting the Sun. Newton was able to derive Kepler's third law using hislaw of gravity. Newton's version includes the mass of both objects, P2 =a3 / (M1 + M2), and can be used for any object that orbits anyastronomical body. In this formula the masses are measured in specialunits called solar mass units. The mass of the Sun is equal to one solarmass unit.If the mass of the second object is very small compared to the firstmass, then to a good approximation P2 = a3 / M1. Solving for the masswe get M1 = a3 / P2. Use this mass formula to determine the mass ofSaturn using data from its moon Phoebe: period of orbit is 1.507 years,average orbital distance is 0.0863 astronomical units.Your calculated mass of Saturn is ____________________ solar mass units.You can convert your result above into kilograms by multiplying it bythe mass of the Sun in kilograms, 2.00 x 10 30 kg.Your calculated mass of Saturn is ____________________ kg.Compare your calculated mass of Saturn (kg) to the actual value.Percent Difference = 100 x (your calculated value - actual value ) /( actual value )Your calculated Percent Difference is __________ %.How close did you get? Explain any possible difference.

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