Calculators | Texas Instruments - Science | What Colour to Paint a Car?

What Colour to Paint a Car?

By David Proctor,

Katanning SHS

If you use or quote from the following programs, please acknowledge the author above.

• The Problem
• Testing a Model
• Fair Testing
• Prediction
• Observations
• Explanation
• Class Exercise
• After the Experiment

The Problem

Does the colour of a car affect the temperature it will reach when it is left in the sun?

Testing a Model

Tin cans are to be used to test how hot they become when they are left in the sun for 15 minutes. The cans are test models before we measure cars.

The cans will need to be painted before use. The colours to be used are black, silver and white. On completing this activity you might like to try different colours.

Fair Testing

1. What factors should we keep the same to ensure that the we are conducting a fair test?

2. Why are we trialing our test on tin cans before we make measurements using cars?

3. Are there any factors that might affect the results of the experiment that we can not control?

Prediction

List the colours in order that you think will get hottest - list the hottest colour first. Explain why you have made this prediction.

Colour		Explanation
Hottest Coolest	10
	9
	8
	7
	6
	5
	4
	3
	2
	1
	0

Observations

Use the temperature probe, CBL and graphics calculator to examine the rate at which the temperature of the cans rise over a period of 15 minutes.

• Up to three temperature probes can be used from the one CBL.

• Chose   CHEMBIO   from the   PRGM   section of the calculator menu. Select temperature probe and enter the number of probes you are using and the channels that the probes are connected to.

• The time graph option will graph the temperature rises for the 3 different cans on the same screen. This allows for a quick comparison.

Explanation

Explain what the results tell you about the relationship between paint colour and the amount that the temperature of the tin increased. Compare the results to your original prediction.

Class Exercise

Get permission to place temperature probes in 3 different coloured cars that have been parked in the sun. Set up the CBL so that it will record the temperature every 10 minutes for the length of a school day.

It is important to place the CBL and calculator in a position that will not get direct sunlight.

Be careful to make sure that the experiment is a fair test. (What factors will you need to keep the same for each car?)

Before you do the experiment: use the results from your tin can experiment to write predictions as to:

1. Which coloured car will record the highest temperature and which car will record the lowest temperature?

2. Will the cars heat up as rapidly or as much as the tin cans? Explain your prediction?

After the Experiment

1. Explain what the data collected indicates about your predictions.
2. Using the graph produced by the calculator, state the maximum temperature, and the time it was reached, in each car.
3. Did the cars heat up at the same rate? Give evidence to support your answer.
4. Apart from colour, were there any other factors that affected the results of the experiment? Explain how you think these factors would have affected the results.

Another set of interesting investigations you could try using the temperature probe are:

• Does the size of the car effect the rate at which it is heated by the sun?
• Does window tinting alter the temperture the car interior will reach?
• Where in the classroom is the best/worst place to be on a hot day?
• What is the temperature difference between being in a shady position or a full sun position.
• Is it hotter to stand on a green lawn or on bitumen?
• Which cools faster: a cup of hot black coffee or a cup of hot white coffee.
• Design and construct a model house and trial different types of ceiling insulation to determine which is most effective at keeping the inside of the house coolest (in summer) and warmest (in winter). Have one probe in the ceiling above the insultion and one in the room beneath the ceiling. Try the house with and without insultation.