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~christina~

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**[SOLVED] A woman pulls a suitcase..what is the angle with the horizontal?**

## Homework Statement

A woman at the airport tows her 20.0kg suitcase at constant speed by pulling on strap angle theta above the horizontal. She pulls on the strap with 35.0N force. The frictional force on suitcase is 20.0N

a) what angle does the strap make with the horizontal?

b) What normal force does the ground exert on the suitcase?

## Homework Equations

[tex]\sum Fx= max= Fcos-f = 0[/tex]

[tex]\sum Fy= may= N + Fsin theta - mg = 0[/tex]

F= ma

## The Attempt at a Solution

a.)

I know that the equations are these to get the solution of the angle however I don't know why the Fy is what the equation states it is. (the equation was given by my teacher and I didn't understand why he gave this equation since it wasn't explained)

The thing is..focusing on [tex]\sum Fy= may= N + Fsin theta - mg = 0[/tex]

I do know why it's = to N-mg but why is it adding Fsin theta?

b.) For this part I'm kind of confused as to the way they state the question.

"what normal force does the ground exert on the suitcase?"

normal force is usually what the suitcase exerts on the ground which is :F= mg

but wouldn't the normal force the ground exert on the suitcase be equal but opposite in direction?

thus..

N suitcase= -N ground

m(-g)= m(g)

Is this fine?

Thanks alot