# Homework Help: Inclined Plane Problem

1. Dec 17, 2007

### Grimly

[SOLVED] Inclined Plane Problem

1. The problem statement, all variables and given/known data
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?

2. Relevant equations
a=F net/m

3. 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!!

2. Dec 17, 2007

### Grimly

<bump>

3. Dec 17, 2007

### 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.

Last edited: Dec 17, 2007
4. Dec 17, 2007

### Grimly

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.

5. Dec 17, 2007

### 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.

6. Dec 17, 2007

### 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?

7. Dec 17, 2007

### Dick

Exactly.

8. Dec 17, 2007

### Grimly

Wait does this mean that the plane is frictionless?

Last edited: Dec 17, 2007
9. Dec 17, 2007

### Dick

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

10. Dec 17, 2007

### Grimly

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

11. Dec 17, 2007

### 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.

12. Dec 17, 2007

### Grimly

Alright i get it now thanks.