Newton's Three Laws of Motion

Definition

Newton's first law is known as the law of inertia. It explains that when an object is not moving it will remain in that state unless affected by a stronger force. He also states that the same is true for objects that are moving. They will continue moving at the same speed and in the same direction unless their motion is overcome by that force with greater strength.

What is the first thing that you do when you get in the car? Hopefully you put on your seat belt. The reason vehicles have this safety precaution is all because of inertia. If your car is traveling at a speed of 75 miles per hour and makes a sudden stop you are still moving at the car's original speed. You will continue to move forward at that velocity until you are stopped by a stronger force. When you wear a seat belt it safely serves as that force rather than the dash or possibly the car's windshield.

Definition

Newton's second law is considered the law of acceleration. It states that the greater the force placed on an object the greater the acceleration. However, if the same amount of force is placed on an object with a greater mass it will accelerate less compared to an object with a smaller mass.

One example of the law of acceleration in your everyday life would be at the grocery store. The harder you push your shopping cart the faster it will travel and vice versa. As you fill your cart with groceries the mass increases, so you must push the cart harder in order to maintain your rate of acceleration.

Definition

Newton's final law is known as either the law of reaction or the law of pairs. This law tells us that for every force applied to an object there will be a second force of equal amount that is aimed in the other direction.

Example

In this picture if I am applying force to the cabinet with my feet and the cabinet is applying a second force back on my feet in the opposite direction. In response to the force coming from the cabinet my body will slide across the floor in that direction.

Actions and Reactions in Your Everyday Life.

Newton's Third Law is included in nearly all aspects of your life. Pairs of forces are present when you are simply walking. The action force is your feet pushing on the ground and the reaction force is the floor pushing up on you. If there was no reaction force you would fall through the floor!