# Homework Help: Application of Newton Law

1. Oct 9, 2007

### saber1357

1. The problem statement, all variables and given/known data
I am trying to understand how these Newton's laws work, specifically with an object on an incline.
If a 5.00kg object is attached to a Newton spring scale on an incline (incline makes 30 degrees with the ground), what reading is the scale giving?

2. Relevant equations
Fx = m*g*sin(theta)
Fy = n - m*g*cos(theta)

3. The attempt at a solution
Since the object is not accelerating upward, the netforce will equal zero. And I can solve for the force in the x direction. But how can I use these numbers to find the tension on the spring scale?

2. Oct 9, 2007

### learningphysics

There are 2 forces in the x-direction... mgsin(theta) and the force the spring exerts (and this is what the spring scale reads)...

the two forces balance each other.

3. Oct 9, 2007

### saber1357

So I can simply ignore everything else, solve for the force in the x direction and what the spring reads is opposite of that?

4. Oct 9, 2007

### learningphysics

yes, I believe so. The object and the spring scale are both on the incline right? If that's the case then the spring scale simply reads mgsin(theta).

is the spring scale attached to the incline?

5. Oct 9, 2007

### saber1357

It's not attached to the incline, but a wall directly behind it. I believe that if the spring scale wasn't attached to anything, then there would be no purpose for it.

6. Oct 9, 2007

### learningphysics

yes, that's true.