Laws of Motion

Laws of Motion

Two cars are travelling down a highway at 100 km/h in opposite directions. Both drivers are tired

from driving all day and cross over the yellow line and hit head on. Crash! The driver of car A has remained

inside the car and has broken ribs due to hitting the steering wheel. The driver of car B however is on the

hood of car A and is pronounced dead at the scene, cause of death, a severe case of disobeying the laws of

physics.

Although both cars were heading at the same velocity one driver ended up dead while another

survived. This seems like a complicated and hard thing to explain and to the untrained person it may seem

that driver A just had plain luck on his side however this is untrue. Using the knowledge of basic physics I

hope to explain why the outcome for each driver was different and could have been avoided.

Sir Isaac Newton was the first man to explain what happens in a collision even before automobiles

were invented. He proposed the idea that an object in motion will continue in motion with the same speed

and direction unless acted upon by an outside, unbalanced force. His theory is better known as the Law of

Inertia. The driver of car B was not wearing a seatbelt and as a result was not connected to the body of the

car. According to Newton’s first law and object, the car, and its occupants, was moving until it hit and

external force, car A. When the collision occurred the car and its cargo changed its motion and direction.

However because driver B wasn’t attached to his car by his seatbelt he continued with the same speed and in

the same direction as the car before the collision. Driver B flew through the windshield and onto the hood

of car A. The windshield and c...

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... large. With a crumple zone much of the kinetic energy is transferred into

heat and sound energy resulting in a much smaller force being applied to the car and its passengers. With a

better crumple zone comes an increase in the time of collision which results in a large decrease in force.

Other safety devices being devised are break away poles, collapsing steering wheel columns, and

side airbags. Each of theses new items is being created to improve the safety of passengers by looking

carefully at the physics of collisions and using Newton’s three laws of motion. I hope that this information

has provided you with a better understanding of what happens in a car crash and has provided you with

enough reason to obey speed limits and to wear a seatbelt at all times while moving in a vehicle because

remember it’s not only the law, its the law of inertia!