When it states "in terms of a, b, c" do you need to use all variables?

[Solweak]

Homework Statement

Derive an expression for the maximum displacement possible for the block that will allow the block to still remain at rest. Express your answer in terms of M, k, μk, μs, and physical constants, as appropriate.

Relevant Equations

Spring force with no direction = kx
static friction force = Mgμs

This is a spring problem

From this, it says I need to answer in terms of kinematic friction which to me doesn't make much sense. I also looked at similar questions online to the "in terms of" problems and they don't use all four variables in their derived equation. Do I not need to use all variables in my derived equation when it says in terms of.

My solution:
kx = Mgμs
x = (Mgμs)/k

 

[Solweak]

Also something to add that further supports the notation against needing to use all variables, in another college board question they had an answer not use all the terms listed.

Question:

--------------------------------------------------------------------
Answer to c ii

source: https://apcentral.collegeboard.org/...-guidelines.pdf?course=ap-physics-c-mechanics

 

[vela]

The problem statement does say "as appropriate" which I take to mean you should use the ones you need. Even if that phrase weren't included, I don't think you should feel compelled to use all of the variables listed.

 

[PeroK]

I'm not sure I understand your question. Some expressions will involve static friction, some kinetic friction, some may involve both. I don't think the question setter needs to tell you precisely which ones apply in every formula. Sometimes, for example, the mass may not appear in a final equation. It's up to you to work out whether this is the case.

 

[Solweak]

The problem statement does say "as appropriate" which I take to mean you should use the ones you need. Even if that phrase weren't included, I don't think you should feel compelled to use all of the variables listed.

Ohh that makes a lot more sense thank you

 

[Solweak]

I'm not sure I understand your question. Some expressions will involve static friction, some kinetic friction, some may involve both. I don't think the question setter needs to tell you precisely which ones apply in every formula. Sometimes, for example, the mass may not appear in a final equation. It's up to you to work out whether this is the case.

The question was just what "in terms of" meant as I originally thought it strictly meant you had to use all the variables listed. Thank you guys for sorting that out for me.

 

[PeroK]

How come a post like this sits around for over an hour and then two of us respond at virtually the same time?