Barbie Car Analysis

Please do the following:

• Test the FRONT BUMPER with an accelerometer attached to Barbie's lap.  Save the graphs and the data table.
• Repeat, but this time, use the BACK BUMPER.   Barbie will be facing uphill in this trial.   Again, save the graphs and the data table.
• Simulate a ROLLOVER COLLISION off of the ramp, where the accelerometer is in the seat belt. (Let Barbie's car go down the hill crookedly, so it rolls off.  Again, save the graphs and the data table.
• Document your car visually, including the entrance point and the seat belt.

Project Report

1.  Make a CLAIM of which BUMPER worked better.  Use screen shots of the data on the Logger Pro to provide EVIDENCE for the trial that worked best, and the trial that worked less effectively.

2.  Compare your ROLLOVER data to the BUMPER data.  Explain how effective you think this was as a structure and WHY. 

3.  Draw a force diagram for the car on the hill  and label the Fweight and the Fnormal

4.  Draw a force diagram for the car on the floor.  Label F(friction), Force(weight), Force(normal), F(applied) and F(net).  CAN YOU CALCULATE THE NUMERICAL VALUES OF ANY OF THESE THINGS?  If so, how can you do it?  Show example calculations (not just writing down values)

5.  Calculate how many g-forces Barbie had acting on her by dividing the accelerometer value by 9.8 m/s/s, the value of 1 g.  

6.  How badly would Barbie have been hurt, do you think, based on the g-force information below?

1) Vertical axis g-force:
a) positive: untrained: 5 g; trained, with special suit: 9 g
b) negative (drive blood to the head): - 3 g
c) instantaneous: 40 g
d) deadly: 100 g (record: 179 g)

2) Horizontal axis g-force
"The human body is considerably more able to survive g-forces that are perpendicular to the spine."
Untrained humans:
a) pushing the body backwards: 17 g
b) pushing the body forwards: 12 g


3) "Strongest g-forces survived by humans
Voluntarily: Colonel John Stapp in 1954 sustained 46.2 g in a rocket sled, while conducting research on the effects of human deceleration.
Involuntarily: Formula One racing car driver David Purley survived an estimated 179.8 g in 1977 when he decelerated from 173 km·h−1 (108 mph) to 0 in a distance of 66 cm (26 inches) after his throttle got stuck wide open and he hit a wall."
Source for all quotes and further information:
http://en.wikipedia.org/wiki/G-force 

Reflection:

• Explain your design process and seat belt rationale.
• How well did your bumper work in terms of a crumple zone?
• Does Barbie survive your collisions?
• Was the Barbie protected from whiplash in your vehicle? How do you know?
• What was the effect of the roll-cage?  
• What have you learned?

Barbie Safety Belts

Car Safety Systems: Barbie's First Test

Take a look at common high-tech safety systems and basic safety systems.

Make a list of at least 5 features you wish to build into your Barbie design vehicle.

Find the Fw of the Barbie and the Fw of the car before testing the vehicle.  Record separately.

http://www.youtube.com/watch?v=Jbg-daPUT_I

Task:  Between now and Wednesday, you will design a safety system for a Barbie and her car.  It must include:

• a seat
• a rollcage
• two different bumpers
• a seatbelt

Barbie or GI Joe must be able to get in or out of the vehicle easily.

Materials are flexible; however, you may not use a balloon or ziploc bag

Be prepared to share your documentation.   You may either type it into a shared Google Doc, or write it and send it to me via a series of .jpgs.

Using Spring Scales

Create a setup like this.  Use two spring scales (by the coffee pot) and a string, as well as a hanging mass.  By sliding the scales apart to create a bigger angle, you will change the tension on the springs.   

Enter your data into a Google Spreadsheet and share with me, please.

Bridge Reflection

Before you test your bridge out, please fill this

PRE_REFLECTION form out.

Test the bridge.   You will need to place it between two stools.   Place material on it, and start adding mass.  You may use 100 g or 500 g masses.

Keep track of:

____mass of bridge (kg)  Remember, 1000g = 1 kg

____mass added to the bridge (kg)   Remember to stay out of the way of the masses.  DO NOT stand under the bridge, or with your head below the bridge.

____weight of the bridge (N)   Weight on Earth = mass(kg) X a(gravity).  The acceleration of gravity on earth is about 10 m/s/s

____weight of the mass added to the bridge (N)

____ length of the bridge (cm)




Take a series of pictures of the bridge

a) before you start  (your group members should all be in this picture)
b) when it has 1 kg of mass on it
c) when it has 2 kg of mass on it
d) when it has 5 kg of mass on it.
e) when it starts to torsion
f) after a bridge collapse

Use these pictures to help you with the reflection, and email me your favorite 3.
Then, fill out the FINAL REFLECTION

bridges

Statics: The Physics of Bridge Design

Go to http://bridgecontest.usma.edu/  and download the 2012 software if it is not on your computer.  Run the install program and decide on your bridge.(pwd: ad9der1)

Your goal for day one is to get a working bridge that is NOT a suspension bridge, and then minimize costs.

You will receive points for

• the weight your bridge can hold
• the design cost of your bridge
• the aesthetics of your bridge design and its build
• the agreement in design size between your bridge and your model

When you get a working design, you will need to save the file and minimize the costs.  When you think you are done, send me a copy of the design file.

Day 2: Building the model:

You may use straws (a hollow core structure) or a bamboo skewer model. Please bring these on Friday, as well as glue guns and glue sticks. Your group size must be 3 or less.

Wednesday

Please go through lesson 1 and 2.   Take notes as you do.

http://www.physicsclassroom.com/Class/newtlaws/

Roller Coaster Evaluation Rubric (roller coaster is due on Wednesday)

Group Members:

The concepts of potential energy, kinetic energy, and transformational energy are shown at different points in the coaster. (10)

The designed coaster is shown to the viewer from the side and in total (3)

Evidence of g-force impact on the rider is explained (3)

The concept of inertia is explained in terms of the rider on the coaster. (3)

The concept of Newton's first law is explained in terms of the roller coaster car and/or track. (3)

An example of Newton's second law, F=ma, is provided. (3)

A balanced pair of forces on the coaster is shown or described. (3)

An unbalanced pair of forces on the coaster ride is shown or described. (3)

A calculation of PE at the top of one hill is provided. (3)

A calculation of KE at the bottom of one hill is provided, using BeeSpi data. (3)

Effects of friction are described (3)

A thrill factor for the coaster is provided by the group, with a rationale. (3)

The presentation/poster/video is well-done, and worthy of a world YouTube or Blog Audience. (3)

A summary of what has been learned is provided by the group (10)

Workday (Wednesday and Thursday)

Kids need to build a sample of their roller coaster.  It must have two hills, or a hill, and a loop.

Measurements to be taken

1.Height of first hill:  (m)

2. Height of second hill (m)

3a and b.. Beespi measurement (m/s) of velocity at bottom of first hill   __ and bottom of second hill ___.

4. Mass of rolling object (g)

5. Length of track measured (m)

Kids must also take a video of their coaster from the side view (use the capture video option on Logger Pro or cell phone) as the object goes down.   Analyze this Video using logger pro as it
a) goes down the first hill
b) goes up the second hill

Determine the velocity at the bottom of the first hill using Logger Pro, and compare to the BeeSpi
Determine the velocity at the top of the second hill using Logger Pro
Determine the velocity at the bottom of the second hill using Logger PRo and compare to the BeeSpi

Kids must take a second video of their coaster explaining WHY their group built it the way it did.  This should be 30-60 seconds long and have all group members talking.

3/3 WORK

I will be calling on Skype to catch up with you.   All material from last week is due tomorrow, 3/4   Give it to Mrs. Deutmeyer, send it to me by email, or send me pictures of what you have done using your phone.

Activities for this week:

Read p. 52 on Hooke's law.   Hooke's law and Force weight are two ways to measure force, which is the formula for Newton's Second Law

Hooke's Law uses the stiffness of a spring to measure the weight of an object.   This is portrayed by the graph on pp. 50 or the words on pp. 52

In other words,

a mass (kg) * an acceleration (usually the acceleration due to gravity on earth ,9.8 m/s/s) = Force (Newtons)

F = m a     is Newton's Second Law

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As we design a roller coaster, we have to worry about the weight of the cart, the weight of the riders, and the weight of the coaster itself.  All these things are important to a roller coaster designer. 

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Read pp. 57-62   Fill out the chart on pp. 62,  AND #9 ON P. 63 and fill it out.  To do this, you will need spring scales (the spring scale drawer is labelled) and a about 200 grams of mass, or .2kg   There are drawers marked spring scales and weights.  Instead of getting in the roller coaster or elevator, the scale will serve the purpose of the elevator, and the weight attached to it (use string or paper clips or weight) will represent the person in the vator.  TAKE A PICTURE OF YOUR TABLE/ANSWERS AND SEND IT TO ME, WITH YOUR GROUP MEMBER NAMES ON IT.

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Skim through http://www.physicsclassroom.com/mmedia/newtlaws/cci.cfm and 

http://www.physicsclassroom.com/Class/newtlaws/u2l1b.cfm

Journal question:   HOW WILL INERTIA AND FRICTION AFFECT MY COASTER?

On our next class day, you will be building a coaster.   You will need to bring roller coaster track (hot wheels) and a hot wheels carr.