Since in the US we almost always measure pressure in pounds per square inch, we will use US units in this exercise. Later, if you wish, you can do the exercise in metric units. If you did the earlier experiment on area, you should already know. The pressure under the heal of a woman's spiked heal can be quite large. Measuring the Power of a light bulb.
Light bulbs come in all different sizes and power ratings.
The small lights on a Christmas tree may be only 5 watts yet the vary large bulbs used in the lamps for lighting a football field can be 1000 watts or more. Power is work or energy per time and this means that a light bulb gives out energy at a rate which will be larger if the wattage of the bulb is large. You can measure the energy a light bulb puts out by using it to heat water. In this experiment you are going to study how fast different wattage bulbs can heat the same amount of water. It is important that you follow the instructions given by your teacher carefully.