Frictional force of car homework

[chengbin]

Homework Statement

A dragster reaches 350km/h from rest to 6.2s. If the car is 800kg and generates a driving force of 14000N, find the force of friction acting on the car.

Homework Equations

The Attempt at a Solution

350km/h = 97.2m/s

$$a=\frac{97.2m/s - 0}{6.2s} = 15.7m/s^2$$

F(friction) = F(net) - F(applied)

= F(net) - 14000N

F(net) = ma
= 800kg x 15.7m/s^2
= 12560N

F(friction) = 12560N - 14000N = -1440N

The solution says 10900N.

Where did I do wrong?

 

[Rick88]

I can't see where you are going wrong..