BY LUKE MOTT

Feeling Pressured? 2013 Lower School Science Fair

Question

Will a tire exert more pressure when the temperature is higher or lower?

Hypothesis

I predict that a tire will exert more pressure when it is

warmer rather than when it is colder.

Background

Pressure is usually measured in Pascals.The mathematic equation for Pascals in Si derived Unit is:1 Pa = 1 _N = 1 _kg_ m2 m· s2

Pa: PascalsN: Newtonm2 : square meter kg: meters · m· s2 : meters per second squared

Background (continued)

Unfortunately you can’t put a pressure gauge on a tire so the entire project was measured in (pounds per square inch) PSI.Here is the metric conversion in SI derived Unit1 psi =  ≈ 6894.757293168 N/m² PascalN: Newton'sm2: square meter

Materials:

1 liter bottle of sodaScissorsKitchen Knife1 Tire1 Tire Pressure GaugeGorilla Tape Refrigerator UnitFreezer Unit

Procedure

Use the Swiss army knife to cut off the top of the soda bottle. Stuff the tire into the bottle with the bike tire stem facing up. Cover the entire bottle with gorilla tape. Then keep the bottle at room temperature, 70ºF, for one hour, and then measure the pressure with the tire pressure gauge.

Procedure (continued)

After you measure the pressure of the first bottle, pump the bottle up to the original psi. Then put the bottle in the fridge at 40ºF; after 1 hour take it out and measure its psi. Re-pump the bottle and put in in the freezer at 20ºF, keep it in for 1 hour. Measure the pressure of the bottle. Re-pump the bottle; put it in the oven at 100º degrees. Then, after one hour, measure its pressure. Do two trials.

Observations: Part One

Please Note: Pressure will not be 100% correct due to escaping air

1st Experiment

Test Temp. Temperature

PSI Pascals(to nearest

tenth)

Ratio (temp to pressure

(PSI) 

1. Freezer Temp.

20 34.5 237,869.1 1: 1.73

2. Refrigerator

Temp.

40 35.5 244,763.9 1: 0.89

3. Room Temp.

75 39.5 272,342.9 1: 0.53

4. Oven Temp.

100 41 282,685 1: 0.41

Graph Number One

Observations: Part Two

2nd Experiment

Please Note: • Pressure will not be 100% correct due to escaping air• The first attempt at over 100ºF(4th Test) blew up the bottle

Test Temp. Temperature

PSI Pascals(to nearest

tenth)

Ratio (temp. to

psi) 

1. Freezer Temp.

20 30 206,842.7 1: 1.5

2. Refrigerator

Temp.

40 32.5 224,079.6 1: 0.81

3. Room Temp.

75 39.5 272,342.9 1: 0.53

4. Oven Temp.

100 40.5 279237.7 1: 0.41

Graph Number Two

Analysis

During the experiment I inflated a tire and measured its pressure in PSI. While it was at a low temperature it exerted less pressure, and when it was at a high temperature it exerted more pressure.

Conclusion

In the end, my hypothesis was correct. Based on my Observations when the tire was in the freezer it exerted less psi than when we put it in the oven. Furthermore, the first time we put the tire in the oven it blew up. The evidence supports the conclusion that more tire pressure is exerted at higher temperatures.

Sources

"Pascal (unit)." Wikipedia . Wikipedia , 21 2 13. Web. 18 Apr 2013. http://en.wikipedia.org/wiki/Pascals

"SI derived unit." Wikipedia . Wikipedia , 28 2 13. Web. 18 Apr 2013. <http://en.wikipedia.org/wiki/SI_derived_unit>.

"Pounds per square inch." Wikipedia . Wikipedia , 21 2 13. Web. 18 Apr 2013. http://en.wikipedia.org/wiki/Pounds_per_square_inch