Physics Connections

Title: Does It Look Closer To You?

Elicitation Questions: Asteroid collisions

1. How is a collision between a meteor and the earth thought to have caused the extinction of the dinosaurs?

2. Could a meteor - earth collision occur in our lifetime?

3. How could we prepare for it?

4. How could our preparations be assisted by looking at a graph of the asteroid's motion toward us?

The Contextual Problem

Background: Motion is constant and everywhere. Even when things seem motionless, they are still moving because the entire universe is in constant motion. A basic part of knowledge about our world is an understanding of motion.

The Situation: A meteor from the asteroid belt is approaching earth. Your consulting group is one of many hired to provide part of the assessment of the unfolding situation. You are supplied with radar and visual data to create mathematical and graphical descriptions of the meteor's motion.

Data for Meteor Still Distant from Earth:

months since sighting: 0 1 1.3 2.5 2.9 3.2 3.6 4.0 4.5 4.9 5.2 5.7 6.3 6.8 7.1

position(*10 ⁶ km): 460 430 411 383 361 343 314 296 273 251 234 209 189 166 138

The Analysis:

1. Use the data to draw a time - position graph of the meteor's approach.

2. Now look at the graph and estimate when it might strike the earth.

3. a) Find the slope of the graph.

b) What is the meaning of the slope?

4. Use the slope value to draw a time- velocity graph.

5. a) As the meteor gets closer and closer to the earth, what happens to its velocity?

b) Then what happens to its velocity as it enters the earth's atmosphere?

6. Now make a single time - position graph to show your answers to 5. a) and b) in a visual form.

7. Finally, make a single time - velocity graph to show your answers to 5. a) and b) in a visual form.