An extraordinary Dutch scientist and inventor Christiaan Huygens studied various topics in physics and astronomy, such as the theory of light waves. Part of his work focused on mathematical pendelum. He was the first to derive the formula for calculating the pendelum period based on other variables, such as its length. In 1656, Huygens constructed the first pendelum clock. For about 300 years, they were the most reliable machine to measure time precisely.

Task: Build a simple pendelum (we do not mean a pendelum clock, just a simple pendelum) with a variable rope length. Build and program a robotic construction that will measure the time period of one swing with a good precision. Try pendelums of several different lengths and with varying initial displacements. Present the measured values in a table and a chart. Can you see and describe any relation?

Some 15 million trucks are riding the roads of the European Union. The transport companies are lacking the drivers and so in the future it is likely that the autonomous transport systems will be in use instead, although a lot of work still remains. Already today, some companies are testing special trucks that communicate with each other and when driving in a row, they exchange the information about the situation on the road and their steering. This helps to improve not only the road safety, but it also decreases the fuel consumption and helps to protect the nature.

Task: Build two trucks that will drive one after another and that will be communicating over a BlueTooth connection. The first vehicle is controlled either by some touch sensors, buttons, or other sensors, or it can follow a line. The first vehicle will be sending its control actions to the second vehicle: speeding up or slowing down, or turning left or right. The second vehicle will receive the message and react consequently. Speed change occurs immediately to maintain the distance, but turning should take place only after it will reach the same location where the first vehicle has turned. The second vehicle will thus follow the first one based on the information received over the BT. It can also monitor the situation and adjust the proper distance using a sensor, if desired.