Demolition Derby Testing!

The thrill  of the crash motivates demo derby enthusiasts.  Our action figure is no exception, which is why s/he needs a great safety harness and bumper arrangement.


Please do the following (Note:  as much as I would like to have an actual demo derby, you can simulate the experience by using a ramp, a pop can, and a wall.  Here is a sample diagram, although yours might be different.

:

• Create a three point harness that simulates a real seat-belt.   A chair with appropriate padding to prevent whiplash should also be included.
• Test the FRONT BUMPER with an accelerometer attached to your doll's lap.  Save the graphs and the data table.
• Repeat, but this time, use the BACK BUMPER.   Your doll 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 the 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 the doll 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 from Wikipedia?

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 effectiveness  of the roll-cage?  
• What else have you learned?