"It's not the speed that kills you...."

@James25 But hitting a feather at 60 mph will not kill you . Mass matters.

Also, cruising along at high speed does not kill you. Change in velocity is what matters.

And mass multiplied by the rate of change in velocity equals force

Hitting the wall kills you not because of the high speed, but because of the rapid change in speed from 60 to 0. The deceleration kills you.

@DrWatson yes I am very much aware of that

@DrWatson you seem to be trying to say that speed is not a part of the equation. My point is that speed plays a role in the equation and is a part of what kills you. There is a big difference between 1 mph and 100 mph.

@James25 The equation is F = ma.

@DrWatson "Newton's second law of motion states that F = ma, or net force is equal to mass times acceleration. A larger net force acting on an object causes a larger acceleration, and objects with larger mass require more force to accelerate. Both the net force acting on an object and the object's mass determine how the object will accelerate."

So if you have a car that accelerates to one mph and hits a cement wall you won't die. But if you have a car that accelerates to 100 mph and you hit a cement wall you will die.

"Newton's Second Law: Force His second law defines a force to be equal to change in momentum (mass times velocity) per change in time."

So whether you describe it as acceleration momentum velocity or speed it is a part of the equation.