Calulate Acceleration from Friction

[halo9909]

Homework Statement

What would be the size and direction of the acceleration of the car? Why would it be constant?

The coefficient of sliding friction between rubber tires and wet pavement is 0.50. The brakes are applied to a 710-kg car traveling 20 m/s, and the car skids to a stop.

So
m=710kg
vi=20
vf=0
Coefficient Slideing friction=.50
a=

Homework Equations

to get the Ff= .50 * 710kg * -9.8 = -3479

The Attempt at a Solution

I have calulated the Force of the friction that the road exerts on the car which is -3479N

From here how wouldyou go about ot calculate the acceleration? since ou do not have dispalcement or time

 

[nicksauce]

Remember, F=ma, so a = F/m. You have F and you have m. The velocity information seems superfluous here.

 

[halo9909]

Negative signs can make a little error, I had 4.9 instead of -4.9 the whole the

never really thought of a=F/m i just plug all of them into the F=ma in the base form