When you apply the brakes we all know it producesthey produce a net force backwards so we all know the resultant force is acting backwards . But when the resultant foceforce acts backwards it doen otdoes not mean that the object should travel backwards .
At the instant the the brakes are applied, the object has a certain velocity , letslet's take it as V1 ehich$V_1$ which is positive, assuming the car moves backwards at the the same instant, meaning it should have a V2$V_2$ which is negative. (Note that: velocity is a vector, so the direction is really important. ) This situation causes the object to have aan infinite decellarationdeceleration, considering the resultant force stays constant .
- DecellartionDeceleration can never be infinity.
- Once the object has a zero velocity, it will never travel backwards, because friction is an opposing force when there is motion ,. Now there is no motion, so no friction .Therefore Therefore no resultant force resulting in no motion.
Normally a graph for velocity when braking is like this.