Choose the sheet for the learner's age. Each prints on a single page. Build the project first, then fill it in together.
Ages 8-10: Predict, test & record
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Slow-Wave Loops · Ages 8-10
Slow-Wave Loop Lab
Predict, flick your loop, and record what the waves do.
1. Predict: when the loop is spinning, a wave on the side moving up will travel...
◯ faster than on a still loop◯ slower than on a still loop◯ the same speed
2. Flick near the top. Count how many seconds the wave takes to reach the bottom (or write 'too fast').
Try
Motor on or off?
Which side?
Seconds to the bottom
3. When I flicked the side moving down near the top, the ribbon...
◯ made a slow wave◯ acted stiff, and the wave rushed away◯ stopped moving
4. Draw your spinning loop. Draw an arrow on each side showing which way the ribbon moves, and a wiggle where the slow wave was.
5. What did you find out?
6. Why do you think the wave is slow on the side moving up?
Ages 11-14: Explain & design your own test
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Slow-Wave Loops · Ages 11-14
Waves on a Moving Rope
Use your spinner to test how a moving rope changes what we see a wave do.
1. Is the wave on your loop a transverse or a compressional wave? How can you tell from the way the ribbon moves?
2. On a still loop a wave travels down at its own speed. Explain why the same wave looks slow on the side moving up but very fast on the side moving down.
3. If the motor turned the loop faster, the slow wave would look...
◯ faster◯ slower◯ the same
4. In a test of the question above, what would you change, what would you measure, and what would you keep the same?
5. Measure the loop's speed: length divided by the time for one trip (time 10 trips and divide by 10).
Loop length
Time for 10 trips (s)
Time for 1 trip (s)
Loop speed
6. Where else do speeds add or subtract like this? (Think of moving walkways, boats on a river, or planes in the wind.)
Answer guide for grown-ups
Homemade Science with Bruce Yeany · Slow-Wave Loops · Answer guide
Answer guide
Ages 8-10: Slow-Wave Loop Lab
Slower than on a still loop.
Open answer: look for effort and careful observation.
It acted stiff, and the wave rushed away.
Open answer: look for effort and careful observation.
Waves on the side moving up crawl slowly; on the side moving down they rush away so fast the ribbon looks stiff. On a still loop they move at an in-between speed.
The wave is going down while the ribbon carries it up, like walking the wrong way on a moving walkway, so it barely gets anywhere.
Ages 11-14: Waves on a Moving Rope
Transverse: each bit of ribbon moves side to side while the wave travels along the ribbon.
The wave moves through the rope at its usual speed, but the rope is also moving. Against the rope's motion the speeds subtract (wave speed minus rope speed), so it looks slow; with the motion they add, so it looks very fast.
Slower (Bruce: the faster the rope moves, the slower the wave travels).
Change: the motor speed (or loop material). Measure: the time for a wave to travel from top to bottom. Keep the same: the loop, its length, the height, where and how hard you flick.
Open answer: look for effort and careful observation.
Examples: walking on a moving walkway or escalator, a boat going upstream versus downstream, a plane flying with or against the wind, ripples on a flowing river.