Help i can't really understand

[dyenz]

what is the acceleration of a certain car if the velocity is constant?? is it zero?

 

[Karmalo]

The acceleration is the derivative of the velocity respect to time so if the velocity is constant, the acceleration would be 0 (m/s^2) (as the derivative of a constant is 0)

 

[dyenz]

what's the meaning of derivative?

 

[Karmalo]

"the derivative is a measure of how a function changes as its input changes"

take a look in wiki: http://en.wikipedia.org/wiki/Derivative

 

[AC130Nav]

what's the meaning of derivative?

Velocity is speed in a straight line. If the velocity is constant, there is no change in velocity, which is what acceleration is, so acceleration is 0 by definition. (Unless your teacher is very sneaky and is talking about the acceleration due to gravity.)

Derivatives are not necessary for this level of physics. Apparently you haven't had calculus, yet.