Activity 2: The Six-cent Top

Materials needed per student:

• 2 1/2 inch piece of 1/4-diameter dowel rod
• scissors
• 1 3-inch square of paperboard (can be cut from cereal boxes)
• 6 pennies
• 6 small paper clips
• "Spinning Tops" Observation Sheet

per class:

• hot glue gun and glue stick

or older students, per group of 4

• stopwatch
• compass
• protractor

Procedure:

1. Give each student a dowel rod. Ask each student to put the point of it down on the floor or table and spin it like a top. "What happens?" (The dowel rod quickly falls over on its side.) Ask, "What does the dowel rod need to work like a top?" (A wider middle or more mass around the middle.) Have students record their observations on the "Spinning Tops" Observation Sheet.
2. If the paperboard circles were prepared in advance, give one to each student. If circle patterns were prepared, distribute a paperboard square to each student and have them share the patterns to make their own circles. For older students, give them paperboard squares and have them make their own circles using compasses and make pencil marks every 60 degrees using protractors.
3. Have each student poke the point of the dowel rod through the starter hole in the circle without tearing the hole any bigger than necessary. The dowel rod should protrude about 3/4 inch. Place a dot or two of glue on each dowel rod to hold it to the circle.
4. Have each student give the dowel rod a spin by twirling it in the fingers like a tops. Ask "Is the top any different in behavior now? What made the difference?" (This is the first variable the will test. You may wish to talk about variables at this point) Let students practice spinning their tops for a few minutes.
5. If students are collecting data, each group should choose one top to experiment with. They should now spin the top several times, timing and recording the length of time the top spins before touching its circle on the table.
6. Have students predict what will happen if they clip six paper clips to their tops and record their predictions. Have them position six paper clips evenly around the top and test their predictions. Ask "Is it now harder or easier to start the top spinning?" (It should be slightly harder to start to turn the top.) "Does the top have more or less spin time now when you release it?" (It will usually have a longer spin time with this extra mass) If students are collecting data, they should now spin the same top again 10 times and record the length of time the top spins.
7. Have students remove their paper clips and hold them in one hand. Have them hold six pennies in the other hand. Ask, "Which feel heavier?"
8. Have students predict what will happen if pennies are glued to the top instead of paper clips and record their predictions. Glue six pennies on each student's circle. Ask again if it is harder or easier to spin and how the spin time has been changed. Remind the students that with each individual change to their tops they are testing a new variable. Groups may again collect their data.

Discussion:

Lead students in a discussion of their observations of the top. Focus the discussion on the variable (mass) and how changes in this variable affected the spinning of the top. Keep a sample of each type of top on hand. Let a student try the different tops if he or she does not remember the feel or performance of the first or second top.

Ask, "How does mass affect the spinning of a top?"

If students were collecting data, they may now compile data into a usable form by averaging and comparing the average spin times for each variable. They can use this data to answer the above question.

Wrap-up:

Let students draw pictures of "Things that spin."

Students may put their observation sheets with the rest of the sheets they have been working on in this series of lessons.

Resources:

Terrific Science Press. Teaching Physics with TOYS; TAB Books, 1995; pp. 59-65.