Solving Work Problem: Kinetic Energy of Toy Car After Braking

[Dwrigh08]

The toy car is sliding with a kinetic energy of 6.4 J when it locks up its tires (obviously, the toy driver slammed on the toy brakes) and slides for 62 cm, while a frictional force of 0.63 N acts against it. What is the kinetic energy (in Joules) of the car after this frictional work is done?

I am not sure where to even start.

 

[mgb_phys]

Work = force * distance. How much energy is lost in braking, how much does it have left.

 

[Dwrigh08]

Since W=Force * distance then W = .63N * .62m, So W = .3906Nm with = .39 J. Would you then subtract the Jules? which would = 6.01 Joules

 

[mgb_phys]

From conservation of energy you know that ke(start) = ke(end) + energy lost.
You know the ke at the start, you have found the energy lost - so ke at the end is easy.