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?

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.