Section 3.1. Impact of speed on force of impact

Your car performs together a an outcome of organic laws and also energy of movement working together. When you journey a 3,000 pound automobile at higher speeds, these pressures are lot greater. You may have actually a difficult time maintaining manage at highway speeds or in unusual instances that need you to make an emergency stop.

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To maintain manage of her car, girlfriend must recognize the effects of these forces. By staying alert and ready come act, girlfriend can apply what friend know and also reduce possible conflicts.

To far better understand crash dynamics (what wake up in a crash), we have to look in ~ what are referred to as the laws of Motion, as discovered by sir Isaac Newton, that is normally recognized as the dad of mechanics.

Newton’s first Law

A body at rest tends to continue to be at rest, if a human body in activity tends to continue to be in motion, unless it is acted top top by an unbalanced external force.

This law explains the concept of inertia. If you are riding in a auto at x speed and have to prevent suddenly, or if your vehicle strikes another object, that is the inertia of your body that resists the stopping, resulting in you to slide forward versus your seat belt.


Newton’s 2nd Law

The acceleration of a human body is straight proportional come the pressure acting on the body, while that is inversely proportional come the massive of the body. The energy an item has as it move is referred to as kinetic energy, or energy of motion. The much faster your auto moves, the an ext kinetic power it has. Kinetic energy is the pressure that a automobile carries and and that need to be absorbed by the car in a crash. More recent cars crumple upon impact and absorb kinetic energy.

Kinetic energy increases substantially as weight and also speed increase. If your rate triples, you require nine time the distance to stop.

Once you know kinetic energy, friend can change to traffic situations ahead of time. You have the right to see how crucial it is to always reduce your rate in an emergency situation. Once you cut your speed in half, you reduced your kinetic energy by four times.


Newton’s third Law

For every force exerted on a body by another, over there is an equal however opposite pressure reacting top top the an initial body through the second.


For every action, over there is one equal however opposite reaction. If over there is a five-pound load sitting top top a table, the load pushes down on the table v a force of 5 pounds. Similarly, the table pushes up on the weight with a pressure of 5 pounds. A basic dynamic instance of this regulation of motion is a whirly-gig lawn sprinkler. The water leaving the arms of the sprinkler exerts a pressure on the eight of the sprinkler, which renders them rotate.

Although friction is not taken into consideration one that the legislations of motion, that is crucial to understand it as it relates to crashes. We have a love-hate partnership with friction. If you room driving your car and have to stop quickly, you desire as much friction as possible; however, to obtain maximum purpose of use from your car, friend want less friction.

One meaning of friction is that it is the resisting force that has to be overcome when one body moves in contact with one more body. One thing we need to know is the the pressure of friction in between two objects sliding together is dependence on the material of the two objects sliding. An instance of this is a tire sliding ~ above the road. Us all understand that the more friction we have, the sooner we stop. Wet roads have less friction 보다 dry roads, so it will certainly take you much longer to protect against on wet roads.1

Newton’s legislations of Motion aid you understand the effect of speed on the pressure of influence in a motor car crash. The quicker your vehicle is travel at the time of the crash, the more kinetic power the automobile has, and also this kinetic power must be dissipated if the auto comes come a protect against (crashes). The greater the speed, the greater the impact – and the higher the hazard of severe injury and also death to the vehicle occupants.

Section 3.2. What wake up in a crash and the ide of 1st, 2nd and 3rd collision

Have you ever wondered what happens within a vehicle when the crashes? human being at crash test labs do. They invest hour after ~ hour measuring, testing and analyzing. They’ve uncovered that in every auto crash, there space actually 3 collisions.

The car’s collisionThe human collisionThe person body’s collisionTHE car COLLISION

During a collision, the automobile crashes come a stop. At 30 mph, a vehicle hitting an item that is not moving will crumple in around two feet. Together the auto crushes, the absorbs some of the pressure of the collision.




The second collision is the “human collision”. At the moment of impact, the driver and passengers in the auto are still traveling at the vehicle’s original speed. Once the automobile comes come a stop, the driver and passengers continue to it is in hurled forward till they come in call with some part of the automobile, such as the steering wheel, the dashboard and the front window, or the earlier of the front seat. Human beings can additionally cause significant injuries come other humans when they collide with each other. Rear-seat passengers regularly hit people in the front chair of the vehicle as they paris forward v incredible force.




In a crash, also after a person body pertains to a complete stop, the interior organs space still moving. Once they stop moving, these inner organs slam right into other guts of the skeleton system. This “internal collision” often reasons serious injury or death. Imagine what happens once someone’s head collides through the windshield of a car. ~ the person stops moving, the brain hits the within of the skull. This could an outcome in a range of injuries, native a gentle concussion come permanent brain damage.



Wear your safety and security belt, consisting of the shoulder harness, properly; it has been proven to work-related in the crash test lab and on the road.

DID girlfriend KNOW?Three the end of 4 crashes occur within 25 miles of home, at a rate of 45 miles every hour or less.About 40% of all fatal crashes take place on roadways where the posted speed limit is 30 miles every hour or less.Motor vehicle crashes cost American taxpayers over 230.6 billion dollars every year.1

Section 3.3. Power absorption in relationship to car design and direction that impact

The energy absorbed by a auto in a crash is very variable. Mental that force at impact is kinetic energy. The formula is K.E. = 1/2 mv2, which equates to: Kinetic power is equal to one fifty percent (1/2) the the massive of the car (m) time its rate (v) squared. In various other words, a VW bug is no enhance for a Mack truck traveling at a similar speed.

Energy is took in by 1) auto design; 2) the area that the auto struck; 3) the type of material; and 4) the assistance in the area that the vehicle. Every vehicles have what is known as a stiffness coefficient value. This value dictates the coefficient of restitution of a given vehicle.

In plain language, let’s take it a round of modeling clay and also a billiard ball. If we drop the billiard sphere from three feet ~ above a marble floor, the ball will go back to or an extremely near the three feet height. The is a value of 1. When we drop the clay round from the same three feet, it continues to be on the floor. There is no return. The is a worth of 0. The billiard sphere is very elastic, if the clay round is really plastic. Vehicles room designed v both plastic and elastic values to absorb power forces in a manner the will minimize the direct forces the reach the automobile occupant(s).

Energy absorb is straight dependent on car speed, angles of collision, and areas of automobile contacts. In any given collision, each auto will endure a Delta V, or adjust in speed, during the minute of collision. Depending upon each vehicle’s initial speed, this Delta V takes just milliseconds. There is very little time for the car components to collapse, bend, fold or crumple in a manner that will protect the precious cargo within.

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A an easy in-line direct rear-end collision will manipulate energy taking in bumpers on the front of the bullet vehicle and also the behind of the target vehicle, if both room passenger-type vehicles. Depending on the speed of the vehicle, energy forces may not be absorbed by the bumper equipment alone. Large trucks carry out not have power absorption bumper systems and mass is much greater, so considerably an ext energy will be sent come the occupants.

Angular collisions are different. Crashes in ~ acute angles may be considered sideswipe collisions, together opposed come 90-degree “T-bone” crashes. Typically, the bigger the angle, the an ext energy is transmitted to the occupant compartment. The angles between the vehicles at collision are referred to as Principal Direction of pressure angles and are equal and also opposite as proclaimed in Newton’s legislations of Physics: “For every action, there is one equal and opposite reaction.”

One essential thing come remember is that the greater the speed and mass, the much more energy and also force is created. No auto can protect people from every crash situation, even with every the security restraint equipment in use. Speed is a significant factor in dictating exactly how much energy the automobile can absorb to defend the occupants.3