how fast do the planets move? investigation what is the order of the planets, from closest to the...
DESCRIPTION
An Astronomical Unit (AU) One Astronomical Unit is the approximate distance between the Earth and the Sun. 1 AU ≈ 149,600,000 km.TRANSCRIPT
How fast do the Planets move?
INVESTIGATION
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?1. Speed = Distance
Time2. Need to know: The orbital distance of eachPlanet and the time it takes for the planet tomove around the sun.
3. What units should we use to represent speed?
What´s appropriate?
An Astronomical Unit (AU)One Astronomical Unit is the
approximatedistance between the Earth and the
Sun.1 AU ≈ 149,600,000 km.
Why is 1 AU an approximate distance and not exact?
1.The Earth´s orbit is an ellipse not a perfect circle.
2.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
Often Mathematicians cannot always findexact answers to problems because it
wouldmake the problem too difficult to solve.
In these cases, we make simpler assumptions.
We can assume that the orbit is circular to decrease the complexity of the problem and find an approximate answer.
Planet Mercury
Venus
Earth Mars
Jupiter
Saturn
Uranus
Neptune
Orbital Radius (AU)
0.38 0.72 1 1.52
5.2 9.45 19.2 30.06
Time to orbit Sun
88 days
225 day
s
365 .25
days
687 day
s
11.9 years
29.45
years
84 years
164.8 years
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.
Planet Mercury
Venus
Earth Mars
Jupiter
Saturn
Uranus
Neptune
Orbital Radius (AU)
0.38 0.72 1 1.52
5.2 9.45 19.2 30.06
Time to orbit Sun
88 days
225 day
s
365 .25
days
687 day
s
11.9 years
29.45
years
84 years
164.8 years
Data (1 AU = 149600000 km)
Pair Challenge 2: a) Find the speeds of all the planets in the
solar system in km/h, km/s and in m/s.b) Look at the answers you have in km/s. Do
you notice anything? Which graph could best show the connection between speed and orbital radius?
Topics DiscussedContent1.12, 1.13 - Speed, Distance and Time6.3 - Circumference of Circles6.1 - Converting between measurements.11.3 - Scatter Graphs and Correlation.1.10 - Significant Figures1.9 – lead onto Standard form.SkillsSimplifying a problem by making
assumptions.Ways of displaying data.Appropriate Answers