Question

A force of 20 N is applied horizontally to a 1 kg mass on a level surface. The coefficient of friction is .2. if the mass is moved a distance of 5m what is the change in KE?

W= change in Ke
Fd= Change in KE
(20)(5)=Change in Ke
200 J =change in Ke

But the thing is how would I incorporate friction since it acts on the mass and the surface? F_f= Fn(meu)
=mg(meu)
=1(9.8)(.2)
=1.96 N
Would i just subtract 1.96N and 20N ?

Answer 1

You almost have it.

Netforce*distance= changeinKE
(20-mu*1*9.8)*5=change in ke

or, you could calculate work in (your Fd) and subtract friction work. You forgot the distance on your fricion calcs.