Guilty Until Proven Innocent

Yesterday, you looked at http://www.edheads.org/activities/crash_scene/swf/index.htm

You must experiment with the WHAT IF scenarios using your pool table.   You also should be watching the information on the 'collecting evidence' as it directly relates to the activities below.

STEP 1:  Collect the data for a collision representing the situation in the edheads crash.  Use two similar sized marbles.

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?   

Momentum during crashes

http://www.edheads.org/activities/crash_scene/index.shtml

Is the activity we will be going through.


You DO have to hand in a set of individual notes.

You DO NOT have to complete all the calculations

Pool Tables

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

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 marginally useful, plywood is 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, 12/16 and bring to class
Step three: Notes and Ideas



Momentum ideas

Basics of Momentum

Click to Run

Notes you can take

Momentum workshop

Explain it in 60 seconds video

Explain it in 60 seconds is a project of Fermilab, a scientific facility located outside Chicago in Batavia, IL.  Fermilab does cutting-edge physics research and astrophysics.  Here's an Explain-It-In-60-Seconds effort on gravity waves.

Using the explain-it-in-60 concept, take the time to create a video that explains a property of force.  You must use audio, video, and text in your composition, and render the video using Windows Movie Maker Live.  Audio, video, and on-screen text must be included.  Graphics or photos may also be used.  The video may be an action sequence, a newscast, a comic adventure, or something else of your choosing.

Your audience is 6th graders.

You will be evaluated using this rubric

You must have a basic script that is at least one page long, typed.  Follow the 2 column script format.

You must have a storyboard.

• Storyboarding for Dummies Link
• Wikihow hints

You will have the rest of Monday and all day Tuesday to execute your project.   Video is due at the beginning of class on Thursday.


Topics:

1. Pairs of forces in amusement park rides, balanced and unbalanced
2. The effects of crashes (momentum and impulse)
3. Net forces
4. Safety gear and Newton's Laws
5. The effects of mass on a sports activity
6. Mass vs. Weight on Earth and the Moon
7. Moving inertia, stopped inertia, and the change of inertia
8. Fun with Newton's laws examples
9. Finding and shifting your center of mass in gymnastics
10. Conservation of momentum in a pool game
11. Friction and the effects of rosin 
12. Shoe differences for friction
13. Crumple zones and net force
14. Some other topic approved by Mapowell

Assessment for Net Forces

Bungee Barbie

There are many types of harnesses and jumps for Barbie.   You will detail the type of harness(es) used and the type of jumps you give for each Barbie.  You must try two different jump styles for each material and keep a careful table of data.

Details on harnesses and jump styles can be found at:   http://www.bungeeamerica.com/jump-styles.html



Set up the equipment, attaching a Barbie on a cord to the force probe.  Connect an accelerometer to Barbie and her harness. Remember that you need to tell the Logger Pro what type of force probe is attached...it may not do so automatically.

Place a motion sensor below Barbie on the ground. Determine Barbie's Fw, and F(net) and Fup Your calculations must be shown at the moment that Barbie is at the maximum extension of the rope going DOWNWARD. All calculations must be summarized in a table when you turn in the lab.  S

Procedures:
Produce as least 6 different graphs by dropping Barbie with different cords. Use the evidence to collect a rationale for the common use of rubber as a bungee cord, and whether it is supported by your data.


Print or save your graphs for each "jump". Clearly indicate which cord or material was used. Also include information such as the amount of force and the time over which the force was applied. Record any relevant observations you saw during the jump.  Hint (this works best if you upload each of the five files to a Google Doc folder, and then share down to your individual machine)

Calculate the Fnet on Barbie and her g-force for each jump using sketch of the graph and data from your trials.  This must be accompanied by at least ONE free body diagram.


Group:  Send me the files you created, with your name, the jump type, and the harness type labeled.

Individual WRITEUP

• Is it possible to design a multi-purpose harness for all sports so that net force is distributed across the Barbie? Explain. This should be based on data you gathered when Barbie parachuted, your seatbelt harness, and this lab.  A picture may be helpful here.

• Explain how the total time for the Barbie to stop jumping can affect a force distribution. (Think carefully: F=ma, but a = change in velocity/change in time)--the motion detector will be helpful her.

• Based on your data, is it possible to argue that there is a better material for a bungie jump than rubber? Why or why not?
• 
  
• Your seatbelt lab, your parachute jump, and the bungie jump all allowed you to gather g-force acceleration data.  Create a table of g-force information and tell me which is the safest situation:  the Barbie bumper crash, the Barbie parachuting, or the Barbie Bungie jumping?   

• What do these labs tell you about extreme sports?

• Write a 4-10 sentence summary of what you have learned.

Parachute Barbie

Links to consider

Parachute Basics
Air Resistance (NASA)
Parachute History (you may want to check out Historical Review)


EACH GROUP WILL NEED TO TURN IN A SET OF CALCULATIONS BASED ON THE INFORMATION BELOW.

Class Prep:  Measure the distance from the landing rail to the ground below

_____m

If we drop an object from the landing rail to the ground (assume no friction), we know the following:

v(i)=____m/s
a=____ m/s/s
d=____ m

What will be the time it takes for the object to land?


You will need to complete the Barbie parachute jump three times today. 


1.  Measure the time it takes to drop the Barbie to the ground three times, using a stopwatch. Calculate the average time ______s

2. Using a force probe that is connected to a Logger pro, measure the Force weight of the Barbie and chute. 

3. Using a(g) = 9.8 m/s/s, determine the mass of Barbie/chute's   ____ kg.

4.  Now you have a slightly different system than the one we first considered.  We know the distance to the ground d=___ m, the initial velocity v(i)=____m/s, and the time(avg) of the three trials _____s

5.  Using the data in 4., calculate the net acceleration of your parachute.

6.  Draw a force diagram of Barbie, the net force, the force weight, and the force up.

7.  Determine F(up).



Take a picture of the Barbie, in its harness, AND a picture of the parachute and harness system.  Email it to me, along with a picture or shared document of your calculations.


Reflection (to be done on Monday)

Riding in the Vator

Watch the three videos.  Then answer the following:

GOING UP

• What happens to the scale when I start moving up?
• When I slow down and stop?

GOING DOWN

• What happens to the scale when I start moving down?
• When I slow down and stop?

CONSTANT MOTION

• What happens to the scale during the middle of the trip?
• When the vator is stopped?

The Reasoning Behind Mu

How would you use your data collected over the last days mu for the ramp and mu for the floor before collision?