September 12 – 16, 2011 Welcome Assignment Take out your planners and write homework assignment Pd. 1 – Elliptical Motion Lab Report due 9/15 Pd.2, 4, 5, 6 – Elliptical Motion Lab Report due 9/16 Get Science Notebook - Draw a diagram of our solar system: include the sun, 8 planets, the dwarf planet, and their orbit patterns. http://www.kidsastronomy.com/solar_system.htm

The Elliptical Path Purpose: To explore planetary motion and the factors that affect its shape. Background Information: Foci = More than one focal point; an ellipse consists of two focal points. Gravity = A force exerted between two objects, distance and mass determine its strength. Inertia = An object in motion stays in motion Heliocentricity = The idea that the center of our solar system is the Sun. Orbit = The gravitationally curved path of an object around a point in space. (Label a diagram of the solar system with at least 4 of the five vocabulary words above.)

The Elliptical Path Hypothesis: If the foci get farther apart, Because… Then the Elliptical Path will have a shape that is… If the foci get closer together, Because… If the foci have no distance between them Because…

The Elliptical Path Materials: Cardboard 2 tacks 2 pieces of String (20cm) and (12cm) Graph paper Pen

The Elliptical Path Procedure Gather all materials Tie a loop with the piece of string (20cm) Place two pins at 5 cm apart Place the loop over the two pins Use your pencil to draw the ellipse Label it with its measurement Repeat for foci distance 4cm, 3cm, 2cm, and 1cm Then create a separate diagram using the 12cm string loop

Data/Observations http://ssd.jpl.nasa.gov/?orbits

September 12 – 16, 2011 Welcome Assignment Get Science Notebook – open to pre-lab write up for the Elliptical Path Lab leave open for checking

Data/Analysis What two variables did we change? Look at your two diagrams analyze what changes the elliptical shape… What do you notice about the elliptical shape as the foci have less distance between them? How does size of the string change the general shape of the ellipses?

Conclusion Questions Part 1 Compare your hypothesis to the data/observations, is your hypothesis refuted or validated? Explain using examples from your data. Error Analysis – Are there any methods in the lab that could have been done better for more precision/accuracy? Explain by giving specific examples and ways to improve the lab.

Conclusion Questions Part 2 What does each variable symbolize in the universe? How does the data collected explain the shape of the Earth and Pluto’s orbit in our solar system? (Research the two planetary orbits and explain how their orbital shape must be formed. Use the word foci and ellipse in your explanation. How does gravity and inertia help create this elliptical shape? How do scientists use this information to help us? Extension – one revolution around the sun is a planetary year, how old would you be on each planet? http://www.exploratorium.edu/ronh/age/