Forces and laws of motion worksheet-Newtons first law

[meredith]

Homework Statement

http://go.hrw.com/resources/go_sc/phy/HF2SR042.PDF

this is the link to the worksheet I am having trouble with. if anyone could help me out that would be great. i got most of it but have a few questions.

Homework Equations

fy=sin(angle) x force
fx= cos(angle) x force
fnet = √(fy^2 + fx^2)

The Attempt at a Solution

1.) F1 + F2 + F3
2.) String 1: x component:0
y component: -Fg
String 2 x component: -F2cos(theta1)
y component: F2sin (theta1)
String 3: x component: F3cos(theta2)
y component: F3sin(theta2)

Number 3 is what I am having trouble with. i know that the Fx net is:
√0+xcomponent String2^2+x component String3^2)
but I am not sure about the y component. is it just the sqrrt of the sums of the squares of the three ycomponenents? or am i missing something?
oh and i think i can do #4 without a problem.

so can someone check my work and make sure its right and help me with #3? thanks!

 

[asleight]

Homework Statement

http://go.hrw.com/resources/go_sc/phy/HF2SR042.PDF

this is the link to the worksheet I am having trouble with. if anyone could help me out that would be great. i got most of it but have a few questions.

Homework Equations

fy=sin(angle) x force
fx= cos(angle) x force
fnet = √(fy^2 + fx^2)

The Attempt at a Solution

1.) F1 + F2 + F3
2.) String 1: x component:0
y component: -Fg
String 2 x component: -F2cos(theta1)
y component: F2sin (theta1)
String 3: x component: F3cos(theta2)
y component: F3sin(theta2)

Number 3 is what I am having trouble with. i know that the Fx net is:
√0+xcomponent String2^2+x component String3^2)
but I am not sure about the y component. is it just the sqrrt of the sums of the squares of the three ycomponenents? or am i missing something?
oh and i think i can do #4 without a problem.

so can someone check my work and make sure its right and help me with #3? thanks!

1) It's in equilibrium...

2) 0, [tex]F_1=m\textbf{g}[/tex].

3) It's in equlibrium in both directions...

4) Sweet.

 

[thomate1]

Hello! It looks like you have a good understanding of the first two problems. For number 3, you are correct that the Fx net is the square root of the sums of the squares of the two x components. For the Fy net, you will need to take into account the vertical forces acting on the object. So the Fy net would be the sum of the y components of all three strings, which would be -Fg + F2sin(theta1) + F3sin(theta2). Then you can use the Fx net and Fy net to calculate the overall net force using the formula fnet = √(fy^2 + fx^2). I hope this helps! Let me know if you have any other questions.