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Air resistance increase with velocity??

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@d!_†oX!©:
Why does the air resistance increase as the velocity of a body increases?????
I have read that in so many books but don't know why it happens......

Ghost Of Highbury:
thats a theory...

The amount of air resistance an object encounters is directly proportional to its surface area and velocity.

nid404:
ok here's the explanation

KE = 1/2 mv^2 , you see when you double velocity you square it and so the kinetic energy goes up by 400% instead of 200%.

For instance, if you are going 10 m/s on a bike and your mass is 50kg then your KE is 1/2* 50kg *(10m/s)^2 = 2500 Newtons of energy.

If you double your velocity to 20 m/s you get: KE = 1/2* 50kg * (20m/s)^2 = 10,000Newtons of force.

Well you can use the same formula almost for resistance, but substitute in resistance for velocity because the same thing happens. When you double velocity , you SQUARE air resistance.
That is why it is so much harder to double your speed when you are riding a bike, because instead of just doubling the air resistance (200% increase in velocity) , you get a 400% increase in resistance.

So just think of it that way. Double velocity and you square Kinetic energy. Double velocity and you also square the air resistance force.

astarmathsandphysics:
Force equals rate of change of momentum. If your car travels faster you are pushing the air in front of you faster hence increasing the momentum and the force you exert increases with speed. But the air exerts am equal and opposite force on you.

@d!_†oX!©:
Thanks a lot guys!!!!!i really appreciate the help from each one of you!!!! :) ;D :)especially nid....it was so easy to understand cuz of that example...
 ;D ;D

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