Isaac Newton(1646~1727) was one of the greatest physicist in the world. Newton’s three laws of motion can describe most of the motion in the universe.
Newton’s First Law of Motion
Every object in the state of uniform motion tends to stay its motion, unless external force is applied to it. This law has a name of Law of inertia. This law is saying that a rock will not move unless someone kicks it. This law is also stating that a moving object will tend to move unless someone or some force stops it.
On Earth, there is a force called fraction, which is a force against any moving object due to collision of air and surface. Because this fractional force works as an external force, moving objects stops. However, in the space, there is no air, so moving object can stay in the same motion in the same speed forever.
Newton’s Second Law of Motion
The relationship between an object’s mass m, its acceleration a, and the applied force is F=ma. It is a very important formula for high school students because it will come up many times in their physics class. The unit of mass is normally, kg, and the unit of acceleration is m/s^2, and the unit of force is Newton, N. For example, if a car is accelerating 3m/s^2 and it has mass of 2000kg, then the applied force on car is 6000N. Be careful with units because to get force in N, you need to multiply acceleration with unit m/s^2 and mass in unit kg.
Newton’s Third Law of Motion
For every force, there is an equal and opposite force, For example, if you push a wall with 50N, the wall is pushing you back 50N. Another example would be throwing a rock. If you throw a rock with 30N, the rock pushes you back 30N. The reason why the rock goes flying while you can stay the same is fraction. Fraction stops you from you moving backward. On ice, there is small fraction. If you throw a heavy rock forward, you will be pushed backward.
Newton’s Three laws of motion are very important laws to understand the behaviors of motions. Some motions, however, do not follow Newton’s law. The examples of such irregulars would be motions of electron. High school does not cover these motions, so high school students do not have to worry about this.
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This article was written for you by Edmond, one of the tutors with Test Prep Academy