Newton’s First Law of Motion
Sir Isaac Newton (1642-1727), an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, is one of the most influential scientist who ever lived.
In Newton’s work, the Principia was published on 5 July 1687, Newton stated what he believed to be the three universal laws of motion. It is said that these laws enabled many of the advances of the Industrial Revolution which soon followed. It was not Newton’s identification of the laws of motion that contributed to the development of machines, instead machines function because of the laws. In other words, things don’t move when you push on them because Newton’s second law of motion identifies the relation between force and motion. From the beginning of time, a force applied to an object caused the object to move. Newton identified and gave mathematical relations between force and motion.
Newton used the Latin word gravitas (weight) for the force now called gravity. For more information about Newton’s Life and his scientific advancements, see Sir Isaac Netwon’s Life.
Newton’s Laws of Motion Explain the Spin Difference Between
A Hard Boiled Egg and A Raw Egg
Newton’s First Law of Motion introduces the term inertia, which is a measure of how easy or how hard it is to move a stationary object. Assuming a boiled egg and raw egg have the same mass, the inertia of the two eggs would be the same if they are moved linearly, meaning in a straight line. But, the two eggs do not rotate or spin the same.
When rotated, the inertia of a boiled egg is less than that of a raw egg. This is because objects spin or rotate around their center of gravity, which is their balancing point. Boiled eggs are solid throughout, thus have a stationary center of gravity making them easier to spin than raw eggs. Raw eggs are solid on the outside and liquid inside. When rotated the center of gravity of the egg changes as the liquid moves around. This sloshing of liquid inside the egg shell makes it harder to spin the raw egg. Raw eggs wobble when spun.
Test the Spinning of Boiled and Raw Eggs
Place a boiled and raw egg on a table. Spin both eggs.
What Happened?
As expected, the boiled egg was easier to spin. It spun faster and longer than the raw egg. This is because the inside of the boiled egg was solid, so the shell and content spun as one solid mass. The liquid inside the raw egg was more difficult to spin because the liquid did not move with the shell.
More to Discover
What do you think will happen if you spin the boiled and raw eggs, and stop them by touching each egg briefly with your finger?
Hypothesis: If the boiled egg’s content moves with the shell and the raw egg’s shell and content do not move together, then touching the eggs will ———————-(What do you think will happen and why?)
Experiment
Test each egg one at a time. Spin each egg, then gently touch the egg to stop its motion. Observe each egg after it stops for a few seconds.
Results:
Both eggs stop spinning, but the raw egg starts to spin again.
Why?
The content of the boiled egg moved with its outer shell. Thus, when the shell was stopped the egg stopped. The content of the raw egg continued to spin after its shell was stopped. In a short time the motion of the spinning liquid inside the shell caused the shell to start spinning.
