A vehicle is moving with a constant velocity of 10m/s
Its mass is 2000kg
If f=ma why is a force felt when it collides with an object (considering 2000 X acceleration (0) = 0N)
Its mass is 2000kg
If f=ma why is a force felt when it collides with an object (considering 2000 X acceleration (0) = 0N)
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Force in collisions is better understood with impulse and momentum.
If we have a 2000kg car moving at 10m/s that strikes a wall we can calculate the initial momentum with
p = mv
p = 2000(-10) = -20000 kg m/s
If the car recoils from the wall at 3 m/s we can calculate the final momentum in the same manner.
p = 2000(3) = 6000 kg m/s
Then Impulse equals delta p
I = pf - pi = 6000 - (-20000) = 26000 kg m/s
If the collision lasts for .2 seconds we can find the average force exerted on the automobile.
26000 kg m /s over .2 s = 230 kN
If we have a 2000kg car moving at 10m/s that strikes a wall we can calculate the initial momentum with
p = mv
p = 2000(-10) = -20000 kg m/s
If the car recoils from the wall at 3 m/s we can calculate the final momentum in the same manner.
p = 2000(3) = 6000 kg m/s
Then Impulse equals delta p
I = pf - pi = 6000 - (-20000) = 26000 kg m/s
If the collision lasts for .2 seconds we can find the average force exerted on the automobile.
26000 kg m /s over .2 s = 230 kN
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This concept is sometimes hard to understand but you gotta think about it this way. Newtons second law talked about the NET FORCE which is the sum of all the forces acting on the object. When you're talking about a car, you have drag from air and friction upon the parts within the car which act in the opposite direction the car is moving and when you sum up these forces they come out to be zero because the negative force component cancels with the positive force component.