How to play Rope Pulse
- Choose a test and read the rope, the pulse, and its speed on the card.
- Remember what travels: the shape and its energy move along; each bit of rope only moves up and down.
- Type your prediction and press Start. The pulse runs along the rope in real time.
- Compare the orange marks with the pulse, the ribbon, or the rope where pulses meet.
What is a wave?
Flick one end of a stretched rope and a bump runs along it. That travelling disturbance is a wave. The bump moves along at the wave speed, set by how tight and how heavy the rope is, but the rope itself goes nowhere: each bit only moves up as the bump arrives and back down as it leaves. A ribbon tied to the rope shows it, bobbing in place while the bump passes. So a wave carries energy and a shape from one place to another without carrying the material. The amplitude is how far the rope moves away from its resting line, up or down. When two pulses meet, the rope's height is simply the sum of the two, and afterwards each carries on as if the other had never been there: waves pass through each other. At a fixed end, the pulse bounces back upside down. Water waves, sound, earthquakes, and light are all waves of this kind: something travels, but the medium stays put.
A focused learning model
The rope is ideal: the pulse keeps its shape and speed and nothing is lost. Each pulse is a smooth bump about 1.2 m wide; in the amplitude test it is one full wave, up and then down. Heights are drawn 5 times larger than lengths. Where pulses overlap the heights are added exactly, and at the fixed end the reflected pulse is the incoming one turned upside down. Runs play in real time. Answers within 2% are right; for the ribbon, anything up to 0.5 cm counts as 0.