![]() ![]() For example, Aristotle thought that weight affected falling objects. ![]() His views on motion were widely accepted because they seemed to support what people observed in nature. The Greek philosopher Aristotle dominated scientific thinking for many years. Stefano Bianchetti/CORBIS/Corbis via Getty Images Nicolaus Copernicus was the first to propose that Earth revolved around the sun rather than the other way around. This illustration shows the Copernican world system. ![]() Before we continue with his other two laws, let's review some of the important history that informed them. Newton owed much to events and people who preceded him. In fact, the marble-and-ramp thought experiment described previously is credited to Galileo. That honor goes to Galileo and to René Descartes. Interestingly, Newton wasn't the first scientist to come up with the law of inertia. Seatbelts hold dummies (and passengers) down, protecting them from their own inertia. When the car hits the wall, the dummy keeps moving in a straight line and at a constant speed until the dashboard applies a force. Why? Because, according to Newton's first law, an object in motion will remain in motion until an outside force acts on it. If the car slams into a wall, the dummy flies forward into the dashboard. Now imagine that a crash test dummy is inside that car, riding in the front seat. Imagine for a moment that a car at a test track is traveling at a speed of 55 mph (80 kph). In fact, seat belts exist in cars specifically to counteract the effects of inertia. You experience inertia in a moving car all the time. Which person in our example would be easier to move? Common sense tells you that the boy would be easier to move, or less resistant to inertia. Remember the object of sumo wrestling is to move your opponent from his position. Let's say the wrestler on the left has a mass of 136 kilograms, and the boy on the right has a mass of 30 kilograms (scientists measure mass in kilograms). ![]()
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