One day, Isaac Newton was sitting underneath a tree, and an apple falls and bonks him on the head. In a stroke of genius and coincidence, Isaac comes up with the theory of gravity and the rest is history…or so the story goes. This simple anecdote actually does a disservice to just how much of a contribution Isaac Newton made to the core of science. While there are many subjects to pick from, today, we are going to focus on the first of Newton’s Three Laws of Motion.
As many of us learned from another famous scientist, Bill Nye, inertia is a property of matter. This is also Newton’s First Law of Motion, and it is actually a very simple concept: an object at rest or in motion will remain at rest or in motion unless acted upon unless something makes it move or stop. So why did it take someone like Isaac Newton–the guy who invented Calculus just to help him understand gravity–to come up with it for us?
The main reason is that in our experience, the law seems wrong. If you throw a ball, it doesn’t keep going forever. It hits the ground and stops rolling after a bit. If you start walking, you don’t just glide on forever. This does not break Newton’s first law though, and that is because there are little forces like the air and the friction of rolling a ball that slow them down. These outside forces are exactly what the law is talking about! If instead you were to throw a ball out in space, it would keep on going forever until it hit something or got pulled in by gravity!
In these demonstrations, we are showing that an object at rest remains at rest. The little metal hex nuts sitting on top of the orange ring are stationary directly above the small opening of the bottle. When the ring is pulled out, the hex nuts do not move horizontally, and instead fall straight down due to gravity!
This idea can be expanded to the table cloth magic trick that you may have seen, but you have to get it just right!
Too see more cool demonstrations with inertia, click here!