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_ m 2 m· s 2 Pa: Pascals N: Newton m 2 : square meter kg: meters · m· s 2 : 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 Unit 1 psi = ≈ N/m² Pascal N: Newton's m 2 : square meter

Materials: 1 liter bottle of soda Scissors Kitchen Knife 1 Tire 1 Tire Pressure Gauge Gorilla Tape Refrigerator Unit Freezer 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 1 st Experiment Test Temp.TemperaturePSI Pascals (to nearest tenth) Ratio (temp to pressure (PSI) 1. Freezer Temp , : Refrigerator Temp , : Room Temp , : Oven Temp ,685 1: 0.41

Graph Number One

Observations: Part Two 2 nd Experiment Please Note: Pressure will not be 100% correct due to escaping air The first attempt at over 100ºF(4 th Test) blew up the bottle Test Temp.TemperaturePSI Pascals (to nearest tenth) Ratio (temp. to psi) 1. Freezer Temp , : Refrigerator Temp , : Room Temp , : Oven Temp : 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, Web. 18 Apr "SI derived unit." Wikipedia. Wikipedia, Web. 18 Apr "Pounds per square inch." Wikipedia. Wikipedia, Web. 18 Apr e_inch