Guilty Until Proven Innocent

Guilty Until Proven Innocent

Problem:

How can you use the conservation of momentum to prove to a judge that you were not speeding and therefore do not deserve a ticket for the collision?

Materials:

Paper, Logger Pro, video, safercar.gov, protracter, ruler.

Procedure:

You leave the school teacher's parking lot and are traveling north when you are broadsided by a car traveling east. The collision occurs in a school zone with a speed limit of 20 mph.  The impact throws you into the band practice field.

Following the collision the police officer determines that both vehicles had a speed of 22 mph (9.8 m/s). The driver of the other car is an adult and claims that you were speeding and consequently should receive a ticket. You are to prove your innocence by using the conservation of momentum.

Research:

What type of a vehicle were you driving?  What type of a vehicle was the other driver riding in?  Look again at the safety and the mass of these vehicles at the NHSTA site (http://www.safercar.gov  ).  Use the same vehicle you looked up earlier this week.

Your vehicle_______________           Mass or weight____________

Their vehicle_______________           Mass or weight____________

Decide on the units for your momentum and record here ____________

Draw a diagram of the two cars just prior to impact. You were headed north, the other car was headed East. Choose a scale (e.g., 1 cm = kg m/s) or freehand draw a diagram of the vehicles before AND after the impact your calculation .  

There are two possible cases.  In Case 1, you were going 20 mph.  In Case 2, they were going 20 mph.  One things for sure.  After the collision, you were stuck together and both of you traveled at 22 mph.

Do one set of calculations for each Case.

STEP 2:  MODEL THIS COLLISION USING two balls of similar diameters but different masses.  Because the collision described above is inelastic, the balls must stick together and slide after impact.

Summing Up (each person does this individually,1/2 to 1 page, and hands it in paper clipped to the diagrams)

1. Qualitatively explain, using your diagrams, how you know that you were not going faster than the adult. Remember that a ticket means higher insurance rates and a large fine.

2. Do you think you were you speeding?

3. How would angles affect your logic?

4. What evidence of impulse or guilt would the police collect in this action?
5.  Based on the safety rating of the vehicles involved, what do you think the extent of the injuries would be?
6.  What role did impulse play in the safety factors present in your vehicle?   

Pool Tables Individual Reflection

Create an INDIVIDUAL  lab report that answers the question: Was momentum mostly conserved in your data analysis?  Include EVIDENCE AND SKETCHES to back up your claim.

Did you have an mostly elastic or mostly non-elastic bumper?  How do you know?

What was the difference between the bumper collision, the 1-d collision, and the 2-d collision on the table in terms of momentum conservation.

Write a conclusion that indicates pictures and explanations of the following: 

• inelastic collisions, 
• elastic collisions
• impulse in a vehicle collision
• one-dimensional momentum
• two-dimensional momentum
• the law of conservation of momentum

Finally, explain why we use pool tables to discuss momentum, and other systems that would work equally as well.

Documentation

You need to get the videos done today and shared with me in a folder.

Go to Google Drive

Make a folder that says,  "Momentum Pool Project"

Right click on it and share with me.

Today's job is to get the videos done.  When that is finished, you will need to do SEVEN of the problems found here for Monday.  You MUST show a picture, write down masses and speeds, and write the momentum equation or the impulse equation that is used.   Since there are 30 problems to choose from, I'm sure you will all have a different mix to share with me.

Pool table documentation and video scripts

HAND IN YOUR PACKET today.


Use your phone or a video capture utility to make the videos.   You may need to convert them, so use a video converter.

You will need to upload each of these items to your Google Docs account.   Share a FOLDER with me, not individual documents.

1. Make a 30-60 second video that shows you and your pool table, it's dimensions, and it's gravity feed system.   Take a picture from above showing the break of the balls.
2. Create a one ball collision with a bumper using a video feed.

3. Comment on the elasticity of your bumper.
4. Create a two ball video between the ball and a second ball that illustrates 1-d momentum.
5. Create a two ball video between the ball and a second ball that illustrates 2-d momentum.
6. Create a two ball video between the ball and the second ball that causes both balls to rebound.
6. Analyze #3-6 using logger pro and the movie feature. Make certain you scale your picture.
7. Print your data.


You must share videos to marciarpowellATgmailDOTcom with your group member names.

Pool Table work

Part of this project of a creating a pool table involves creating a scaled model.  This can be done with Google Sketchup, on graph paper, or using Autocad or another program of choice.  Include a top, and one side view to indicate the ball return system.


You can start with a series of Google Tutorials--I like this one, but there is an entire channel devoted to Sketchup tutorials at http://www.youtube.com/user/SketchUpVideo





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This activity is adapted from High Tech High

You will be building a table top pool table.
Requirements

The Detailed Sketch must:
-- Be scaled-down from a full size pool table
-- Be no bigger than 65 cm * 130 cm
-- Be drawn on the computer (I would suggest Google Sketch)
-- Represent the ball return system that is gravity fed (not simply pockets)

The Pool Table must:
-- Include handmade billiard balls (golf balls allowed), cue sticks, & racking triangle
-- Be functional   (You may make ONE modification---having 4 ball holes instead of 6 ball holes)

The Ball Return System must:
-- Gather ALL the billiard balls in one area
-- Be easily accessible by the players
-- Be seamlessly integrated with the pool table

Step one: Make a materials list (cardboard is able to be used, plywood is perhaps better), assign roles, and create a sketch of your design (please submit the sketch to me via email)
Step two: Create your pool table by Monday, 11/19 and bring to class
Step three: Notes and Ideas



Momentum ideas