Newton’s Laws of Motion

Are you familiar with Newton’s three laws of motion?

Newton's Cradle

In 1687 Sir Issac Newton published his works entitled Philosophiæ Naturalis Principia Mathematica. As intimidating as that may sound it is simply Latin for “Mathematical Principles of Natural Philosophy.” In this work he compiled three laws that are now renownedly known as Newton’s Laws of Motion. In this blog we will consider what the three laws are, why they matter and some modern-day examples to make them relatable.

  1. Newton’s First Law of Motion

An object at rest tends to stay at rest and an object in motion tends to stay in motion. However either can be changed due to an application of force.

This law is essentially Galileo’s concept of inertia and is known simply as the Law of Inertia. Newton stated this law to set the parameters for his next two laws. I’ll use a Fidget Spinner for an example. Before spinning, the object would likely not start spinning on it’s own! However, after spinning one, it would continue to spin forever if it were not for the effects (forces) of friction and gravity. It would be interesting to see an astronaut try this experiment while in space! 

 

2. Newton’s Second Law of Motion

Force equals Mass times Acceleration F=ma

This law explains the connection between the mass of an object, the acceleration and the resulting force. This equation also works backwards to determine the mass or acceleration of an object. For an example let’s use two vehicles on a crash-test course to determine their differences in force during impact. Let’s say Vehicle 1 is a Military Hummer with a weight of 7,700 lbs and Vehicle 2 is a Smart Car with a weight of 3,000 lbs. It seems we all know which would have more force but how do we reach that conclusion? Can Vehicle 2 impact with more force than Vehicle 1? Newton’s Second Law tells us. Lets take a look. Vehicle 1 weighing 7,700 lbs traveling at 60 mph will hit the wall dealing a force of 462,000 N. Vehicle 2 traveling at the same speed will only deliver 180,000 N of force. For Vehicle 2 to exert the same amount of force on the wall it would need to be traveling at 154 mph. That’s over twice as fast!

 

3. Newton’s Third Law of Motion

For every action there is an equal and opposite reaction

This Law is pretty easy to understand. Newton is telling us that for each and every force between two objects there is another force in the opposite direction of equal magnitude. An example of this is Newton’s Cradle. The cradle holds 5 balls of equal weight and size suspended from a foundation. If one ball is lifted and released it will hit the other four motionless ball and stop. However, the force will travel through three of the balls and cause the fourth to swing into the air as if you had pulled it up like the first! This scientific gadget can be used in different ways to yield different results (such as lifting two, three or even four of the balls). However, the law still remains the same. What we learn is that the ball that stops exerts its force toward the other four while at the same time the four exert a force on it.

 

Newton's Cradle

 

Now you have it! We really hope you enjoyed learning with us. Please come back to find more scientific knowledge and experiments! And feel free to share this page with any interested friends, family or students!