Finding friction force and coefficient when applied force causes acceleration

[pinkyjoshi65]

[SOLVED] URGENT---Frictional force

A force of 1.6N is applied to a box of mass 1.8Kg. It accelerates 0.6m/s^2. Determine Ff and the coefficient of kientic friction.

K so I knoe how to do this. But in the textbook, it has been done in a different way.

So what I did is Found the net force using F=ma.
Then i subtract from 1.6 and get Ff.
Then use the formula mk= Ff/Fn

In the book they took Ff=ma
Which is the right solution?

 

[Kurdt]

Well $F_{net}=F_{applied}-F_k$ where $F_k$ is the force due to kinetic friction. So with a bit of manipulating one can see that the friction force will be the applied force minus the net force which can be worked out from the acceleration of the block.

 

[pinkyjoshi65]

And fnet is MA

 

[Kurdt]

And fnet is MA

Yes.