To investigate the how effective the length of crumple zones are and to see how to protect occupants during a collision.
DEPENDANT VARIABLES
Force exerted upon collision by measuring the initial velocity and time it takes for collision.
CONTROLLED VARIABLES
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Distance cart travels before collision
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Material of Cart (cardboard)
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Same motion cart
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Same mass
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Same plasticine human
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Same speed prior to collision
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Position of occupants
INDEPENDANT VARIABLES
The independant variable is the length of crumple zone.
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16 sheets of cardboard paper (2 sheets stuck together to make one crumple zone)
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1 Tape and gluestick (to attach crumple zone together and also to attach it to the cart)
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1 Gluestick (to stick the 2 sheets of card board paper together and make crumple zones)
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1 Meter Ruler (To measure everything when setting up the experiement)
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Scissors (to cut out crumple zone)
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1 Pencil (To record data and make the crumple zones)
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1 Motion Cart
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1 Laptop (To access Logger Pro)
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Plasticine (to make a human figure for the cart)
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1 Ramp (for the cart to travel down)
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1 Brick (so the cart will bump into)
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1 Chair (to place the ramp on)
VARIABLES
MATERIALS
AIM
HYPOTHESIS
There will be four different lengths of crumple zones, 2.5 cm. 5 cm. 7.5 cm and 10 cm. I believe that the shorter the crumple zone on the cart, the higher the velocity and force exerted upon collision. To find out the force I will use the formula: F=mv/t where F = the force exerted upon collision (N), m = the mass of the object (kg), v = the velocity of the cart upon collision (m/s) and t = the time taken for collision (s).
METHOD
1. Ramp is lined up with the chair, with the angle of the ramp to the floor being 26.23 degrees.
2. The distance betwwen the end of the ramp and the brick is 0.4m
3. The 2.5 cm long crumple zone is attached to the cart
4. The cart is placed so that the front of the cart is 90 cm up the ramp, traveling a distance of 1.3m in total before hitting the brick.
5. The cart is then released, travelling down the ramp and into the brick.
6. The velocity upon contact and time taken for collision was then measured and recorded using logger Pro.
7. The velocity and time were recorded and used to calculate the force exerted upon collision using the formula F=mv/t.
8. This process was repeated for each crumple zone length twice
RESULTS
Results after testing 4 different lengths of crumple zones twice each as well as without a crumple zone.
Initial velocity:
Min value: 1.612
LQR: 1.6685
Median: 2.004
UQR: 2.112
Max value: 2.197
Range: 0.585
IQR: 0.4435
Mass:
Range: 0.01
IQR: 0.008
ANALYSIS
After completing the experient on how effective crumple zones were, we discovered that as the time taken for collison increases, the force exerted upon collision decreases. Throughout this experiment, you can see that the time taken for collision for the first test is longer than the second tests. During our experiment, we realised that there were some problems that needed to be improved. The first problem we had was the placing of the brick. We placed the brick too close to the end of the ramp by 40 cm and the cart with the 10 cm crumple zone attached to it was also around 40 cm making the experiment harder the get accurate results. The second problem was the material of the crumple zone. We stuck 2 sheets of cardboard paper together to make on crumple zone, but unfortunately, that wasn't strong enough that after the first test the crumple zones already have a blunt corner making the second test less accurate. If you used another material that was hard but light at the same time then the results would more likely be more accurate. To improve our experienment, having other safety features would have been a good idea, such as adding a roof, cushioning or a seatbelt. This way, the occupant would be more safe and won't fall off the cart.
CONCLUSION
My hypothesis is somewhat wrong but also right at the same time as it shows that the average time taken for collision for 2.5cm crumple zone is 0.2583 seconds which is the longest compared to the other results. All the results are different. To put it in order, the length of the crumple zone that had the highest velocity was 2.5 cm then 7.5, 5 and finally 10 cm. There isn't a specific order. As for the force exerted upon collision, the 10 cm crumple zone was the highest with 7.688 Newtons followed by 5 cm, 7.5 cm and 2.5 cm. The Crumple zones were not too effective as the occupant kept flying off the cart.
