Forces and velocities of a sliding box

[tiffanyg]

1. a box of mass 12 kg slides at a speed of 10 m/s acros a smooth level floor, where it enters a rough portion 3.0 m in length. In the rough portion, the box experiences a horizontal friction force of 72N.

a) how much work is done by the frictional force?
b) what is the velocity of the box when it leaves the rough surface?
c) what length of rough surface brings the box coompletely to rest?


I don't know how to do it!

 

[SeanGillespie]

a) What is the equation for work done? What you need to calculate should be quite obvious.

b) You are given the force of friction, what is the equation for Force? You should be able to calculate what you need to calculate the reduced velocity (you will need a SUVAT equation here also).

See if that helps at all... check back with your answers...