Understanding The Physics Behind a Rear End Collision

This blog is for people seeking to understand how injuries are caused by rear-end collisions. The purpose of the blog is to gain a betterunderstanding of the cause for your pain, so you can more intelligently discuss treatment with your doctor.  

Rear-end accidents can be dangerous to the passengers and driver in the front vehicle. Occupants usually have little warning that a crash is about to take place. With no warning, there is no time to take evasive action or brace for the impact. And so, the human bodies in the front-vehicle absorb most of the physical forces released in the crash. These strong physical forces can result in surgery or life-long pain that causes loss of enjoyment to life.

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The energy of a moving object is called kinetic energy. When a rear vehicle impacts the vehicle in front, the kinetic energy in the rear vehicle transfers into the front vehicle.The faster the rear vehicle moves, the greater the kinetic energy transfer to the front vehicle.  Kinetic energy increases with mass and speed. For example, a compact car striking a van at 20 mph has far less kinetic energy to transfer than a loaded 80,000 pounds semi-truck striking the van at the samespeed of 20 mph. And so, vehicles traveling at high rates of speed and vehicles that are heavier will transfer more kinetic energy upon impact to the front vehicle, than an impact from a lighter or a slower vehicle. The greater the mass or acceleration of the striking vehicle, the greater the force it exerts on the front vehicle and its occupants. This explains why even a brief impact at 20 mph can cause significant acceleration of the head and neck.

When the rear striking vehicle impacts the front vehicle,the kinetic energy from the rear striking vehicle creates momentum. Momentum pushes the front vehicle forward with the kinetic energy transferred from the striking vehicle.  Because the kinetic energy in the striking vehicle is transferred to the front vehicle, the striking rear vehicle decelerates (slows down) quickly, while the vehicle being struck accelerates (speeds up) quickly. This sudden energy transfer happens in milliseconds, not seconds. The transfer of kinetic energy and the creation of momentum are controlled by three basic rules of motion that Issac Newton discovered.

Newton’s First Law of Motion – All objects that are at rest or in a state of constant motion will stay at rest or in motion that proceeds in a straight line unless an external force is applied.

Newton’s Second Law of Motion – Force is equal to the mass of an object multiplied by its acceleration with both mass and acceleration having a direction and magnitude.

Newton’s Third Law of Motion – Every action has an equal, opposite reaction, which means that when one object exerts an external force on a second object, the second one will exert a force that is opposite to the first one and equal in its magnitude.

Now that you have a better understanding of these physical laws that control a rear end crash, you know that your pain has a scientific basis in the laws of physics. Your pain is not “in your head.” It results from your body being stretched forward and snapped backward so fast you do not notice because the crash overloads your senses.  

Have an informed and productive discussion with your doctor. Ask your doctor to explain the parts of your body stretched, torn, or broken by the forces in the crash. Once you identify the parts of your body that suffered damage, then you can focus on effective treatment and determine what treatment is working for you.

I hope this blog helped you understand how the laws of physics apply to your rear end crash.  At RedStone Law, we handle rear end crash cases every day.  Please call on us if we can help you!

(copyright©RedStone Law/redstone.law™).

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