Car Physics: Understanding Newton's Laws of Motion

Sir Isaac Newton’s three laws of motion are manifested in almost every activity which goes on in daily life. From a running car to a bird flying, Newton’s three laws of motion are ubiquitous. In fact, more than 99 percent of activities in the physical world are governed by these laws. Newton proposed the three laws of motion to explain how planetary motions work, how any object that has mass responds to an external force, and several other significant phenomena.

First Law of Motion

The first law of motion defines two facets of motion. The first speculates the behavior of objects which are stationary while the second predicts a moving object’s behavior. The first law says that “a body remains at rest or moves in a straight line of constant velocity as long as no external forces act on it”. To illustrate, a car will remain in motion unless an external force by means of a brake is applied on it.

Second Law of Motion

Newton's second law of motion predicts the behavior of an object in which the forces which acts on an object is not balanced. The second law states that “a body acted on by a force will accelerate such that force equals mass times acceleration” (F=ma). Hence, the net force determines the acceleration of the object. To illustrate, as a car gains more acceleration (by means of the accelerator), the more force it will exert when it collides against a tree or a physical structure. 

Third Law of Motion

The third law states “for every action there is an equal and opposite reaction”. It refers to the conservation of energy. The third law also mentions the contribution of force. A force is essentially a pull or push on a particular object which is a result of interaction with another object. In case of a car accident, the force with which the car crashes into the tree would result in the tree exerting the same amount of force on the bonnet, and damage it. The directions of the forces are opposite.

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