Sunday, February 20, 2011


Hi, we're Johanna, Renee and Ashley and this is our year 10 Science Assignment.
We are researching the functions of different safety features in vehicles. Here is our work.

Saturday, February 19, 2011

Part A: Research

Seatbelts are used in almost all motor vehicles. They are made up of two flexible but strong pieces of cloth, one that goes around the waist and then a shoulder strap that starts from the waist and then goes diagonally across the chest and to the opposite shoulder. The purpose of a seat belt is to reduce the risk of the passenger moving within the vehicle in the event of a crash.
A locking system within the seatbelt mechanism locks the seatbelt from moving in the event of a sudden jolt. This stops the passenger from moving further and absorbs the kinetic energy. 
The law of inertia means that even when the car stops, the body inside will continue moving at the speed of the car, not only that, but without a restraint such as a seatbelt the internal organs will also continue to move inside the body. 
Many deaths in car accidents as caused by the heart being pierced by the rib cage 
because the passenger was not wearing a seatbelt. 

Here is a video of a seatbelt crash test:

Head restraints are head rests that are located in the top of most car seats. In the event of a rear impact crash the head restraint prevents whiplash injuries to the neck. A whiplash injury is when a car is hit and with the sudden stop the head of the passengers head goes flying backwards. The head restraints prevent whiplash because it is something to support behind the head in the event of a crash.

    Here is a video example of a POOR head restraint: 

Crumple zones are the front and back of a car that have been specifically been designed to crumple and absorb the impact of a crash instead of the cabin that holds the passengers. The front and rear of cars are made of weaker materials compared to the stronger materials that the cabin is made out of. The crumple zones have been a huge part of the development of safety features on vehicles.

Here is a video demonstrating how crumple zones work in the event of a collision:

The design of the airbag simply came from the idea of having a soft pillow for your head to fall onto in the event of a collision. The airbag is triggered by a large impact and it acts as an additional safety feature to the seatbelt because it restrains the head from hitting the dashboard and therefore preventing serious head injuries that could take place without the protection. 

Here is a slow-motion video on an airbag crash test:

Thursday, February 17, 2011

Part B: Report

 Science Investigation
Road Safety Experiment
Safety Feature: Head Restraints

Aim: The aim of this experiment is to test the efficiency of head restraints with two simulated car crashes, one with and one without the safety feature.

Hypothesis: The rate of impact or deceleration will DECREASE when the head restraint is used. Also without the head restraint the plasticine dummy will either sustain damage to the head and neck or lose its head completely.

·        2 Dynamics Trolleys
·        A slope
·        Plasticine
·         An accelerometer
·        Toothpicks
·        Styrofoam
·        Tape

Our dummy in the vehicle with no safety features
1.     1.     A crash test dummy was constructed using plasticine for the body and tooth picks for the joints.

2.     A slope was set up and the two dynamics trolleys were put into places, one at the top of the slope and the one with the head restraint at the bottom.

3.     The accelerometer was attached to the dummy’s head and set up on the computer.
4.     The dynamics trolley at the top of the slope was let go and allowed to roll down and collide with the rear of the other trolley that was stationary at the bottom, it to travel forward while- according to the law or Inertia- the head of the crash test dummy remains stationary. This is what causes whiplash. 
Our dummy got whiplash

5.     The reading from the accelerometer was recorded.
6.     The steps above were repeated again but one of the dynamics trolleys had a head restraint added; this was made from toothpicks, Styrofoam and tape.
7.     All readings and results were recorded. 


The first time we attempted this experiment successfully without a head restraint, the rate of deceleration was around -190m/s ² and the neck was severely bent back.

Here is a video of the impact:

Here is the graph of results from WinTec: 

Add caption

The second time we conducted the same experiment but with the addition of our safety feature. As hypothesized, this decreased the rate of deceleration and prevented the dummy's head from whipping backwards. 
The rate of deceleration was only -125 this time.

Here is a video of the second impact:

Here is a graph of the results from WinTec:

For comparison, here is the deceleration results from both the tests in one graph:

See how that one safety feature made all the difference?

Discussion/ conclusion:
It has been proven now that head restraints do decrease the rate of deceleration and prevent whiplash and serious neck injuries in the event of a collision as long as the head rest is adjusted properly and secure.

These results show the utmost importance of safety features in cars, not just head restraints but all the others. Our poor dummy got whiplash, but if it was a real person in that car they would have died a gory death. These days cars are just too fast to not have safety features, because speed makes all the difference to the impact. Putting on a seatbelt and adjusting a head rest- it's not that hard, it should be second nature to everyone. So many accidents and deaths could be prevented if the safety features were used correctly and without fail. 
So the moral of this is always make sure your safety features are working. Put on your seatbelt, test your airbags, adjust your head restraint. It's not rocket science. 

Tuesday, February 15, 2011