Coding classes in Bridgend

Every number in the model is invented. Two cars of 1,000 kilograms hang either end of a rope over a pulley, 15 metres apart in height. The bottom car carries 800 kilograms of material. Water poured into the top car's tank makes it heavier; once the difference in weight beats the friction, the cars start to move, one falling and one rising. Physicists call this an Atwood machine. The learner writes the force balance in Python: the pull is the weight difference minus friction, and the acceleration is that pull shared across everything moving. From the acceleration come the journey time and the speed at the end.

Below about 911 kilograms of water, nothing happens: friction wins. A little more gives a slow, gentle lift, 941 kilograms for a 20 second trip. Pour in more and the lift gets faster, but the extra water is mostly wasted. With 1,000 kilograms, 80 per cent of the energy the water gives up goes into raising the load; with 1,500, only 53 per cent does, and the cars arrive carrying 84 kilojoules of motion that the brakes must absorb. The learner finds the 20 second answer two ways: by rearranging the formula, and by trying values in code until the time matches, then checks that both agree.

Then a classic bug. Friction always opposes motion, but it is easy to write it with the wrong sign so that it helps. Do that, and the program claims 695 kilograms of water is enough, when in fact the cars would not move at all. A simple test catches it: at exactly the claimed minimum, the net force should be zero, and with the wrong sign it is not.

Catching a single wrong sign before it matters is why a Bridgend teenager should keep learning to code in 2026. The longer argument is in why teenagers should still learn to code in 2026.