Sir Isaac NewtonThe three laws of motion as laid out by Sir Isaac Newton are manifested in nearly all activities that go on in everyday life – including car crashes. From a flying bird to a racing car, these laws governing motion are ubiquitous. As a matter of fact, nearly 99% of all activities in our physical world are usually governed by these laws. Newton’s Laws of Motion are very important when engineers design airplanes, sports equipment, cars, trains and toys among other motion equipment. In this article, we explain Newton’s 3 laws of motion in a car crash.

Newton’s Three Laws of Motion In Car Crashes

Newton’s First Law Of Motion

Newton’s first law of motion states that a body in motion will continue moving in the same speed as well as in the same direction, or if at rest, it will continue doing so until it is acted upon by an external force. In other words, objects have a natural tendency to continue doing what they were doing until acted upon. In the absence of an external force, a body in motion will maintain the state of motion that it was in or will continue being in its state of rest. This law is normally referred to as the law of inertia.

This law is best exemplified when driving trucks or cars. As a matter of fact, a body’s tendency to continue moving is a very common cause of various transportation injuries. For example, let us consider a case where a car accidentally collides with a stationary wall. When a car collides with a wall, an external and unbalanced force acts on the car, which leads to the car being abruptly decelerated to rest. All other passengers inside the car are also decelerated to rest in case they are buckled up. When you are tightly strapped to car, you will also be in the same motion state as the car.

When a car accelerates, passengers will tend to accelerate with it. When it decelerates, passengers also decelerate with it. If the car is going at a constant speed, the passengers will also maintain the same constant speed.What happens where the passengers did not wear the seat belt?

Should a car stop abruptly after a collision with the wall, the passengers won’t be sharing the same motion state as the car. Using seat belts ensures that there are necessary forces to accelerate or even decelerate motion. When a seat belt is not used, the passenger will tend to continue with their state of motion. Thus, they will be propelled from the automobile and then be hurled onto the air.

Newton’s Second Law of Motion

The second law of motion by Newton states that an objected acted upon by the force will undergo acceleration in such a way that the force equals the mass multiplied by acceleration. Mathematically, this is represented as F=ma. In other words, it states that the force that is applied in the crash is proportional to mass of impacting cars. This means that the bigger the force of impacting cars, the bigger the force applied, which implies a greater destruction. The reverse is also true. If the mass of the impacting vehicles is smaller, less force will be applied, meaning less destruction in general.

Hence, the acceleration of an object is determined by the net force. As a car or a truck gains more acceleration (through the acceleration), it will exert a bigger force when it collides with a wall.

Newton’s Third Law of Motion

This law states that action and reaction are equal and opposite. In short, for every action, there will be an equal an opposite reaction. The law is about conservation of energy and also mentions contribution of force. Essentially, a force is defined as a push or a pull on a certain object and this is due to interaction with that object. In the context of a car accident, it means that the force that a car crashes into a wall leads to the wall exerting same amount of force upon the bonnet, which results to damage. The forces’ direction will also be opposite.

So when a car hits a wall – the wall also hits the car. Also that’s why driving on ice is so difficult – the icy road means less friction so the car cant push the road as hard and the road can’t push the car.

Newton’s Three Laws of Motion In Car Crashes

Newton’s 3 Laws of Motion are very important in understanding car physics. Understanding them will enable you to understand the science behind a car collision and why it is important to wear a seat belt.