Work, Force, Acceleration, and speed of a box attached to a spring

[032050]

Homework Statement

A 5.5kg box is attached to a spring which is attached to a wall. The box is subject to a force of 90N moving it from its equilibrium to a position 40cm away, the coefficient of kinetic friction is 0.300.
a. what is the work done by the applied force over the 40 cm?
b.what is the magnitude of friction between box and surface?
c.what is the speed of the box at 40cm

*I appologize for my formulas looking this way I don't know how to make them look proper*

Homework Equations

a. work=F*dcos
b.Ff=UkFn (opposes motion)
c.conservation of energy
Ek=E(force applied)-Efriction-(Espring?)
Ek=0.5m(v)^2

The Attempt at a Solution

a. I know i have to use the work equation but my question is what is the force is it the Fapplied-Ffriction or just Fapplied?
b.Im pretty sure that this is just plug and chug with the formula where Fn=Fg
c. My only question is should I include the Espring in the calculation?

Thanks a lot in advance!

 

[ideasrule]

The Attempt at a Solution

a. I know i have to use the work equation but my question is what is the force is it the Fapplied-Ffriction or just Fapplied?

Since you're trying to find the work done by the applied force, it should be Fapplied. If you were trying to find the total work done on the box, it would be Fapplied-Ffriction.

b.Im pretty sure that this is just plug and chug with the formula where Fn=Fg

Yes.

c. My only question is should I include the Espring in the calculation?

Yes, because that's part of the energy of the system. However, the question doesn't provide k, and without this piece of information it's unsolvable. Is this a mistake on your part?

 

[032050]

ya that's my fault i was re-writing the question to make it shorter thank you for the help!