The pupils build a truck on which the smartphone is fixed as a tone generator. Another smartphone is used for measurement. The frequency shift can be illustrated by the waterfall diagram or the shape of the audio spectrum. However, correct graph reading must be practised.
Alongside the pure observation of the phenomenon, the velocity of the truck can be calculated in the last task.
The pupils
About 15min are needed to build the truck.
Around 30 minutes are required for the observation of the phenomenon and application of the equation.