How Hot Is It?

Some machines produce a lot of heat when they are used, and some produce such a small amount of heat that it is difficult to notice that heat is produced. Look at the pictures below to see how much heat is produced when these machines are being used. Notice the temperature given below each photograph. The difference in temperatures shown on the right shows how much heat is produced when the machine is used.

Toaster
Off		On	Difference
77 F		212 F	212 - 77 135
Lamp
Off		On	Difference
77 F		89 F	89 -77 12
	Bicycle Pump
	Standing	Being pumped	Difference
	77 F	95 F	95 - 77 18

Look closely at the graph of this data.

Analysis:

1. Did each item start at the same temperature?
2. Which object had the greatest change in temperature?
3. Which object had the smallest change in temperature?
4. Did any of the results surprise you?

Try It:

Work with a parent, teacher or other adult work to measure temperature changes for other machines.

Materials:

• Thermometer
• Lab worksheet or science journal

Procedure:

1. Record the name of the machine on your paper.
2. Decide if the machine uses mechanical or electrical energy.
3. With adult help, measure the temperature of the machine before turning it on, and record it on your lab sheet. This is the "Off" temperature.
4. Set the thermomer near the machine and turn on the machine.
5. Leave it on for five minutes.
6. Caution: the thermometer may get hot enough to burn you. Have an adult help you with this.
7. Record the temperature after five minutes. This is the "On" temperature.
8. Subtract the "Off" temperature from the "On" temperature.
9. Graph the temperature difference on your paper.

Try other machines.

Use this lab worksheet as you do this activity.