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INVESTIGATION. How fast do the Planets move?. What is the order of the planets, from closest to the sun to furthest away?. How fast are you travelling right now ?. What information would a scientist need to investigate the speed of an object?. Speed = Distanc e Time
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INVESTIGATION How fast do the Planets move? What is the order of the planets, from closest to the sun to furthest away? Howfast are youtravellingrightnow?
What information would a scientist need to investigate the speed of an object? • Speed = Distance Time 2. Need to know: The orbital distance of each Planet and the time it takes for the planet to move around the sun. 3. What units should we use to represent speed? What´s appropriate?
An Astronomical Unit (AU) One Astronomical Unit is the approximate distance between the Earth and the Sun. 1 AU ≈ 149,600,000 km.
Why is 1 AU an approximate distance and not exact? The Earth´s orbit is an ellipse not a perfect circle. There are slight variations in the Earth´s Orbit.
Problem that we now face: How do you find the circumference of an ellipse? Formulae do exist but it requires advanced mathematical techniques to derive. Are there any shapes that are slightly more simple than an ellipse that we do know how to find the circumference of?
Assumptions in Mathematics We can assume that the orbit is circular to decrease the complexity of the problem and find an approximate answer. Often Mathematicians cannot always find exact answers to problems because it would make the problem too difficult to solve. In these cases, we make simpler assumptions.
Data Pair Challenge 1: a) The approximate speed of Mercury is 172800 km/h. Use the data to confirm this. b) Change your answer to part a) into km/s and then m/s. Write these answers to 3 significant figures.
Data (1 AU = 149600000 km) Pair Challenge 2: Use Excel to findthe speeds of all the planets in the solar system in km/h, km/s and in m/s. Look at the answers you have in km/s. Do you notice anything? How could would represent this information in a more visual way?
TopicsDiscussed Content 1.12, 1.13 - Speed, Distanceand Time 6.3 - CircumferenceofCircles 6.1 - Convertingbetweenmeasurements. 11.3 - ScatterGraphsandCorrelation. 1.10 - Significant Figures 1.9 – lead onto Standard form. Skills Simplifying a problembymakingassumptions. Waysofdisplaying data. AppropriateAnswers