How to Solve an Inclined Plane Problem: Finding Mass with Acceleration and Angle

[Grimly]

[SOLVED] Inclined Plane Problem

Homework Statement

A box is accelerating down an inclined plane at a rate of 2m/s/s. If the plane is angled at 40degrees, what is the mass?

Homework Equations

a=F net/m

The Attempt at a Solution

I have absolutely no idea how to go about solving this problem. I am a newbie to physics and have tried to think of a way to solve this but without other forces I'm lost please help!

 

[Grimly]

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[Dick]

It doesn't matter what the mass is. I don't think you've stated the problem correctly. On an inclined plane with a given inclination and value of g, all masses will accelerate at the same rate.

 

[Grimly]

It doesn't matter what the mass is. I don't think you've stated the problem correctly.

Well i don't think I've stated the problem incorrectly, this is possibly my teacher has due to this question came right off my HW assignment.

 

[Dick]

Maybe the question is bad, but the force along the plane acting on the object is mg*sin(40). Since F=ma, ma=mg*sin(40). The mass cancels. You can't possibly determine it.

 

[Grimly]

Hm does that mean that all objects regardless of mass will accelerate at the same speed given that g remains constant as well as the angle?

 

[Dick]

Hm does that mean that all objects regardless of mass will accelerate at the same speed given that g remains constant as well as the angle?

Exactly.

 

[Grimly]

Maybe the question is bad, but the force along the plane acting on the object is mg*sin(40). Since F=ma, ma=mg*sin(40). The mass cancels. You can't possibly determine it.

Wait does this mean that the plane is frictionless?

 

[Dick]

So this means that the question was trick and that the mass can't be solved without more information?

If your instructor is prone to trick questions like this, the answer would be yes.

 

[Grimly]

If your instructor is prone to trick questions like this, the answer would be yes.

Thank you very much for the help, also though does this mean that the plane mentioned is frictionless?

 

[Dick]

If the plane isn't frictionless all of the relevant forces are still proportional to m, as is the acceleration. m will still cancel. You need some force entering that is not proportional to m to be able to determine it.

 

[Grimly]

If the plane isn't frictionless all of the relevant forces are still proportional to m, as is the acceleration. m will still cancel. You need some force entering that is not proportional to m to be able to determine it.

Alright i get it now thanks.