Make your own free website on Tripod.com



Physics and Car safety
Airbag/Egg Lab

PURPOSE: To discover why airbags are so important in collisions and how they work.
 
MATERIALS:
~ Raw eggs
~ Bed sheet
~ Table
~ Scale
~Stopwatch
 
PROCEDURE:
1) Two people hold the edges of a bed sheet  2 metres from where the egg will be thrown.
 
2) Another person throws the egg into the bed sheet and records the time it takes for the egg to hit the sheet. Do 5 trials with the bed sheet.
 
3) At the same time another person is responsible for measuring and recording how far the sheet was displaced.
 
4) Set up the same situation but this time throw the egg 2 metres away from the edge of a table. Record the time and displacement for 5 trials.
 
5) Find the velocity for each trial by using the equation 
v=d/ t. Then find the average velocity in each situation.
 
6) Using knowledge about collisions, compare why the egg broke and didn't break in each situation.
RESULTS: 

Trial #
Distance
Time
Velocity
Egg broke yes/no
Displacement (x value)
1
2 metres
1.78 s
1.12 m/s
NO
0.095 m
2
2 m
1.23 s
1.63 m/s
NO
0.095 m
3
2 m
1.39 s
1.44 m/s
NO
0.08 m
4
2 m
1.34 s
1.49 m/s
NO
0.085 m
5
2 m
1.29 s
1.55 m/s
NO
0.09 m
Average
   
1.45 m/s
 
0.089 m

Trial #
Distance
Time
Velocity
Egg broke yes/no
Displacement
1
2 m
1.72 s
1.16 m/s
Yes
0 m
2
2 m
1.89 s
1.06 m/s
Yes
0 m
3
2 m
1.68 s
1.19 m/s
Yes
0 m
4
2 m
1.79 s
1.12 m/s
Yes
0 m
5
2 m
1.55 s
1.29 m/s
Yes
0 m
Average
 
1.73 s
1.16 m/s
   

Result after eggs thrown at the table edge
picture025.jpg

OBSERVATIONS:
1) The bed sheet provides more support to the egg then the edge of the table does.
 
2) The egg does not break any time that it is thrown against the sheet but it breaks every time it hits the table edge.
 
3) The sheet had a diplacement when the egg hits it but the table does not.
 
4) The velocity in the sheet experiment where greater then those in the table experiement.
 
CALCULATIONS:
(bed sheet)
Using the idea that the sheet provides more support becasue it has 'give' means that the sheet acts like a spring. Using the following formula we can see why the egg does not break in this case.
1/2m(v)*=1/2k(x)*
*=squared
In the bed sheet experiment the sheet was displaced as the egg hit it (x). Filling in the formula we get:
1/2( 0.15kg)(1.45 m/s)*= 1/2k(0.089m)*
k=0.3982
This means there is a spring constant which means the sheet acts like a spring providing more 'give' and allowing the egg not to break.
 
(Table)
In the table experiment the eggs broke. We can see that because the table was not indented meaning that there was no displacement (x value) that the table does not act like a spring. Filling in values into the equation we get:
1/2(0.15kg )(1.16 m/s)*=1/2k(0)*
 k=0
Therfore the whole answer is zero showing that the table does not act like a sping, and provides no 'give' to the egg causing it to break.
 
 
 
 
DISCUSSION:
     The reason the egg does not break when it hits the sheet is because of the material it is made of. The sheet has more 'give' then the table does. This is shown by the fact that the table does not have a displacement when the egg hits it but the sheet does. As the egg hits the sheet the sheet dents where the egg lands providing more support and causing less damage.
     This experiment can be compared to a person in a car collision and the effects airbags have on them. The bed sheet represents the airbag and the table edge represents the dashboard edge. The results of this experiment clearly show that airbags help in front end collisions.
     Some errors that may have occured are that the velocity in the bed sheet experiment were higher then those in the table edge. This could be because the timer was not stopped at the exact second that the egg hit each material. This error should not have effected the outcome of the experiment because a higher velocity means a higher momentum causing the egg to have a greater chance to break which it did not happen as the egg hit the sheet.
 
CONCLUSION: From this lab we can see that airbags do help people in front end car collisions because they provide more support then when a person is shot forward in the steering wheel or dashboard.
      
 

Home | The importance of seatbelts | The Use of the Airbag | Impulse | The use of Headrests in a Collision | Friction | Brakes | Airbag/Egg Lab | Friction Lab | Questions | Answers | Statistics | Glossary | Links