Journal Entry - Take out your science journal and answer the following question(s) (use drawings as appropriate):

What keeps our solar system in shape?

Materials:

• String - 1 meter long
• Four large metal washers
• Stopwatch, timer with seconds, or clock with second hand
• Student worksheet (copy from below or printout as a .pdf document.)

Procedure:

1. Tie two washers on the end of the string.
2. Swing it overhead, securely holding one end.
3. Count the number of revolutions it makes in ten seconds.
• Use the person’s nose as a reference point.
4. Repeat Step 3.
Average the two trials.
5. Fold string in half and repeat Steps 3 and 4.
6. Add two more washers on the string.
7. Repeat Steps 3-5.
8. Complete the remainder of the worksheet.

Student Worksheet

Name ____________________________________________

Problem: Which combination of washers and string do
you think will go the fastest?

Hypothesis: ____________________________________________

____________________________________________

 Data Table Experiment First Test Second Test Average 50 cm., 2 washers 100 cm., 2 washers 50 cm., 4 washers 100 cm., 4 washers Your experiment:

Analysis Questions:

• What did the size of the orbit do to the number of

• Which of the planets take longer than the others to
revolve around the sun?

• What effect does mass have on a planet’s revolution?

• What would happen if there was no gravity?

• What would happen if planets’ forward velocity were
changed (e.g. slower, faster)?

• What did your experiment show?

Conclusion: Remember to restate your hypothesis, and the
correctness of your hypothesis, and explain what you
learned. Use the back of your worksheet.

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