In Launchpad, if there’s one scientist we can’t get enough of, it’s Sir Isaac Newton. Although he lived around 300 years ago, the influence of his brilliant ideas still pervade many of our interactive exhibits and, if asked to name a famous scientist, his name is never far from people’s lips. A true giant of maths and physics, it wasn’t until Einstein that scientists found a different set of shoulders to stand on in order to see further.
Much could be said about his work in optics (he named the spectrum, for example) or his work in aiding the entry of pets into the home (supposedly, he invented the cat flap), but it is his work into classical mechanics that we constantly refer to in Launchpad, i.e. how stuff moves.
The Water Rocket is a perfect example of his laws of motion. In this hourly demonstration, a mixture of air and water is pumped into a plastic bottle, leading to an increase in pressure inside the bottle, so that, when the launch button is pressed, the “rocket” speeds down a track at up to forty miles an hour.
It is Newton’s third law of motion that is most obviously in evidence here: Every action has an equal and opposite reaction. When the air and water fly out of the end of the bottle with a certain force, this pushes the rocket in the opposite direction with an equal force.
Newton’s second law (The force moving an object is equal to its mass multiplied by its acceleration, or F=ma) sneaks in too, as the fact that the bottle is lighter than the ejected air and water means that it undergoes a greater acceleration from the same force, and so it flies further and faster down the track.
All of these laws, as well as many other scientific ideas, were written down by Newton in his impressively named book, Philosophiæ Naturalis Principia Mathematica. This book (understandably often shortened to simply Principia) was written entirely in Latin, as was the style at the time, and was published in 1687. And there is a copy in the Science Museum, in the Cosmos & Culture gallery.
It is difficult to appreciate how important this book was to the world of science. As well as being ground breaking to physics, it also introduced the world to mathematics involving calculus. Rarely has a book been packed with so much!
Although there are controversies surrounding Newton and his work, particularly regarding his treatment of contemporary scientists Hooke and Leibniz, there can be little doubt that the impact he had on physics deserves recognition. So go and see the book in which the principles were all written down and then go to Launchpad and see this exciting physics in action.
Ben is an Explainer at the Science Museum.
If you are a teacher planning a visit to Launchpad with your students, you can find out more information here.