real science for today's homeschooler

Rotational Motion with a Pinwheel

Rotational Motion with a Pinwheel

Kids love to play with pinwheels. Whether you buy one at the store or make your own (pinwheel making tutorial), add a little Physics to the fun!

1. Use a string and ruler to measure the outside distance around the outside of the pinwheel.

2. Mark one spot on the pinwheel in some way. Use color, a piece of tape, etc. Just make sure the mark is very visible, even when the pinwheel is spinning.

3. Have your child practice watching the pinwheel in motion and counting each time the pinwheel makes a complete revolution. (When the mark on the pinwheel goes all the way around and returns to the same spot.) Move on to practicing counting exactly 10 revolutions. When your child has this down, move on to step 4.

4. Use a stop watch to measure the time it takes for the pinwheel to make 10 revolutions. Repeat 5 times, then average the 5 trials to get the “average time” for 10 revolutions.

5. Divide the average time by 10 to get the time for 1 revolution.

6. Calculate the speed at which the outside of the pinwheel was spinning by dividing the distance around the outside of the pinwheel (step 1) by the average time for 1 revolution (step 5). Your child has just calculated the rotational speed of the pinwheel!

To extend, repeat using different sources of “wind” to move the pinwheel at different speeds. Add a weather component by repeating on consecutive days to compare the wind strength. Older children may find it interesting to compare the actual wind speed (use a local weather app) to the speed of the pinwheel rotation. Look for patterns and mathematical relationships between the two.

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Calculate Speed While Encouraging Exercise

Calculate Speed While Encouraging Exercise

We all know that kids have a lot of energy. Put that energy to good use by combining a physics lesson, a math lesson, and some good exercise! All you’ll need is an energetic kid, a tape measure, a stopwatch, and a safe place for your child to run.

Calculating Speed

1. Pick out a “track” that your child can run safely. Select a distance appropriate for your child to run several times.

2. Help your child measure the distance of the selected track with the tape measure. You can measure with any units: yards, feet, meters, etc. Have your child record the track distance.

3. Measure the time it takes for your child to run the selected track. If possible, measure the time in seconds. Record.

4. Introduce the formula used to calculate speed:  speed = distance / time

Depending on the math level of your child, help them calculate their speed by dividing the distance of the track by the time it took to run it. Older children can calculate speed using long division. For younger children you may want to introduce the usefulness of technology by showing them how to get their answer with a calculator.

5. Repeat the run with the same track, or a different one as long as your child is interested and energetic. Challenge them to improve their speed with each run.

As an extension of the lab, students can compare their speeds when a) wearing different types of shoes, b) running on different surfaces, or c) running courses of different lengths. Any of these options will increase your child’s interest in the lab, as well as give them extra practice with division . . . and a little more exercise!

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