Impact forces and cushioning

How many “g’s” does a football player’s brain undergo when ramming an opponent? Does the front end of a car always need to take such a beating? These questions may seem unrelated, but they are unified by the physics of impulse and cushioning. Read the text aloud
Impact forces on the brain when tackling in footballPlay a sport such as football, ice hockey, or lacrosse, and sooner or later your head will almost certainly experience an abrupt impulse. Recent studies suggest that the human brain has a 75% chance of being concussed when it experiences a 100g acceleration (which corresponds to a force of roughly 1,400 N!). In the hope of reducing concussion risk, new football helmets are being designed with flexible face masks and foam layers of varying densities. If the helmet’s cushioning can increase the amount of time the head is decelerated, then the forces imparted on the player’s brain are reduced. Padding likewise reduces the forces felt by other parts of a contestant’s body. Read the text aloud Show “<i>g</i>” forces
Impact forces on a person when in a car crashThe same reasoning lies behind many features of today’s automobiles. While it might seem odd to make a car crash last longer, increasing its duration is exactly what improves the odds of survival for the vehicle’s occupants. Consider a collision that abruptly stops your 35 mph (15.6 m/s) car. If your body mass were 60 kg, your initial momentum would have been roughly pi = 936 kg m/s. You might have transferred that momentum to the steering wheel in a dangerous 100 milliseconds (0.1 s) if it were not for several life-saving technologies such as the crumple zone. The corresponding force of 9,360 N is approximately the weight of your car, and it might be sufficient to kill you. The front end of the car, however, is designed to collapse in the event of a crash—rather than remain rigid—thereby extending the time of the collision. The force imparted on the passenger in the case of a crash is reduced. An easily crushed engine compartment is not a flaw but a well-designed, possibly life-saving feature. Read the text aloud
Anything that increases the time over which a collision occurs will reduce the deceleration of the occupants and decrease the forces imparted on them. Seat belts and airbags are both vehicle technologies that are designed to do just that. Read the text aloud

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