Electricity

Electricity - who needs it? Electricity is great, but it's amazing what you can do without it. This week: some ingenious everyday inventions that work without electricity. Here's the first: the original car airbag, invented by John Hetrick 1952/3, which was powered entirely by genius! 1. In the car crash detector (red), there is a heavy weight (2, blue) held to the left by a spring (yellow). If the car crashes, the weight pushes the spring to the right. This pulls open an air valve (4, light blue). The open valve lets high-pressure, compressed air rush out from a cylinder (5, green) into the airbag (6), blowing it up and saving your life. Modern airbags use electronics and explosive chemicals to fire open much faster - but the original invention was much simpler.