Teachers TryScience

Note: This lesson includes an instructional video ("The Lesson") to assist teachers in doing this lesson.

Estimated time requires: 40 to 45 minutes

Student Activity

This activity involves grouping your students. I like to use groups of four. Each student has a role in the group.

Student #1: Materials manager: When asked by your teacher, retrieve materials. At the end of your discovery session, you and your colleagues must clean up area completely. Dispose of materials properly.

Student #2: Recorder:Completely, accurately and neatly write down all necessary information. Use tables, lists, diagrams and so on. To record the group's explanation of circumstances.

Student #3: Manager: Be sure everyone knows exactly what they are doing. Gently remind people to stay on task and contribute productively. Take lead role in safety. Be an encourager to be sure everyone shares their good ideas.

Student #4: Reporter: You are in charge of clearly communicating your group's results, orally and in writing back to the entire class.

Steps in solving the problem

1. Please see Activity Sheet (pdf) and Data Sheet (pdf).
2. Hold the dowel at both ends as shown in Figure 1.
3. Raise the 1-kg mass by winding up the string on the dowel as shown in Figure 2.
4. Keep the winding motion steady so that the string winds up and the mass rises at a constant speed. Practice raising the mass in this manner several times.
5. You are now ready to have your lab part­ner measure the time it takes for you to raise the mass a distance of 1m. (using the meter stick)
6. At a signal from your lab partner, begin to raise the mass at a constant speed by winding the string on the dowel.
7. Have your lab partner use a stopwatch to measure the time required for the bottom of the 1kg mass to reach the top of the meter stick. Record this value under Table 1.
8. Reverse roles with your lab partner and allow them to repeat steps 3-6.
9. The size of the force that was needed to raise the 1-kg mass is equal to the weight of 1 kg. The distance that the 1-kg mass was raised is the distance between from the floor to the top of the meter stick, which is 1m. Record the values for the force and distance in Table1.
10. Calculate the work you did to raise the 1-kg mass and record this value in Table 2.
11. Calculate the power you developed lifting the 1-kg mass. Record the value in Table 2.