Earth Science Lab - Weebly



The Expanding Rubber-verse!

Names: _______________ ________________ Date: __________________Hour: _______________

Learning Target: I will visualize the movement of galaxies through the universe at different speeds using a rubber band model.

Scientists say the universe is expanding. What does this mean? In this lab we will explore what it means to live in an expanding universe.

If the universe is not expanding then all the galaxies should be going away from us at the same speed. A plot of their speed v. distance should look like this.

Speed should be constant.

Question: What would galaxy motions look like on a graph if the universe were expanding?

Hypothesis: If the universe were _____________ then the motion of the galaxy on a graph would look like

_______________________________________(draw picture of what your graph would look like)

Materials:

Rubber band and ruler

Procedure: (The dots on the rubber band will represent “galaxies.”)

1. Use a ruler to measure how far the galaxies are from the left edge of the rubber band while the rubber band is in a relaxed position. REMEMBER: You are measuring from the left edge of the rubber band to the closest edge of the galaxy (dot) EACH time you measure to a new galaxy (dot). The locations of the galaxies are the Initial Distances. Record this data in the table.

2. Now stretch your rubber band slow for about 2 secs. Have your partner hold the end of the rubber band in this position. Now measure again from the left edge to the beginning of EACH galaxy (dot). The locations of the galaxies are the Final Distances. Record this data in the table

Data Table

|A |B |C |D |E |

|Galaxy # |Initial Distance (cm) |Final Distance (cm) |Change in Distance (cm) |Speed |

| | | |(C-B) |(cm/s) |

| | | | |D/2 |

|1 |  |  |  |  |

|2 |  |  |  |  |

|3 |  |  |  |  |

|4 |  |  |  |  |

|5 |  |  |  |  |

3. Subtract the Initial Distance from the Final Distance to find the Change in Distance. Record it in the table.

4. We will assume for everyone that it took 2 seconds to stretch our rubber bands. Calculate the distance moved by each galaxy in one second by dividing the change in distance by 2. This is the speed (remember speed is equal to distance divided by time). Enter this result in the final column –E of the data table.

5. Now do as American astronomer Edwin Hubble did: plot the speed as the dependent (Y) variable and the Initial Distance as the independent (X) variable.

Make sure to include the following:

Title

Label and unit for x axis

Label and unit for y axis

Scale for x-axis______________

Scale for y-axis______________

6. What type of relationship does your graph show? (circle)

linear constant none

Take a look at the graph below, this is exactly what Edwin Hubble saw. He realized that the movement of galaxies were explained by the expansion of our Universe.

[pic]

7. When we look at galaxies, nearly all of them are red-shifted, What does this mean?

8. Take a look below at the picture below:

a) Are the red waves longer or shorter?

b) Are the red waves moving toward or away from the center of the galaxy?

c) Are the blue waves longer or shorter?

d) Are the blue waves moving toward or away from the center of the galaxy?

[pic]

And the farther away they are, the faster they are going! Only the expansion model fits our plot. So…we are NOT in the center, just as Copernicus said!

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Speed

Distance

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