physics lab help needed

[quantumnumber]

ok, the lab I am working on deals with vectors. I am stuck on a part of the lab dealing with the component method. Here is a link to the lab, this might help a little more in explaining what I am trying to do:

http://faculty.genesee.edu/macrittenden/b/lab/3.htm

I have part 1 done, finding the resultant graphically.

What I am stuck on is part 2 - the component method.

Force 1 is 6.0 newtons at an angle of 0 degrees - right on the x-axis. Force 2 is 6.1 newtons at 85 degrees. Force 3 is 9.0 newtons at 223 degrees.

 

[quantumnumber]

oh, and try not to laugh too hard, this is my first physics class ever

 

[origin]

What part are you stuck on?

Edited to add - your data looks good. Did you look at the example calculation? Basically all you have to do is substitute your numbers into the equation and 'plug and chug'. Just remeber the apparatus isn't moving so the forces should add up to zero and don't get confused between radians and degrees.

 

[Shpaget]

Well basicly to calculate a x component of a force vector you use:
Fx = Fxcosß
Note that:
x in Fx is subscript
x in Fxcosß stands for multiplication
ß is angle between positive part of the x axis and the direction of the vector (measuring counterclockwise).

For y component you use:
Fy = Fxsinß

When you have multiple force vectors you use:
Fx = F1xcosß1 + F2xcosß2+ F3xcosß3 + ... + Fnxcosßn
Fy = F1xsinß1 + F2xsinß2 + F3xsinß3 + ... + Fnxsinßn

These two formulas are great because you don't need to change + and -, sin and cos are going to tell you whether it's + or -.
For example:
You have two forces:
F1 = 10 N ß1=30°
F2 = 15 N ß2 = 200°

Fx = 10xcos30° + 15xcos200°
Fy = 10xsin30° + 15xsin200°

Fx = 8,66 + (-14,1)
Fy = 5 + (-5,13)

Fx = -5,44 N
Fy = -0,13 N

Since you got both components negative your vector will be in the third quadrant.

To get the intensity (module, scalar whatever you want to call it) of that vector use:
|FR| = square root (Fx^2 + Fy^2)
Note that |FR| has an arrow above F to indicate that it's a vector, R is subscript, | | means module.

|FR| = 5,4416 N

To calculate the direction (angle ßR, resulting angle) you can use:
tg ßR = Fy/Fx
tg ßR = 0,239
ßR = 1,369°
IMPORTANT:
You must add another 180° to get correct angle, since you know your vector is in III. quadrant.

So your vector is:
FR = 5,4416 N
ßR = 181,369°

 

[origin]

Well basicly to calculate a x component of a force vector you use:
Fx = Fxcosß
Note that:
x in Fx is subscript
x in Fxcosß stands for multiplication
ß is angle between positive part of the x axis and the direction of the vector (measuring counterclockwise).

For y component you use:
Fy = Fxsinß

When you have multiple force vectors you use:
Fx = F1xcosß1 + F2xcosß2+ F3xcosß3 + ... + Fnxcosßn
Fy = F1xsinß1 + F2xsinß2 + F3xsinß3 + ... + Fnxsinßn

These two formulas are great because you don't need to change + and -, sin and cos are going to tell you whether it's + or -.
For example:
You have two forces:
F1 = 10 N ß1=30°
F2 = 15 N ß2 = 200°

Fx = 10xcos30° + 15xcos200°
Fy = 10xsin30° + 15xsin200°

Fx = 8,66 + (-14,1)
Fy = 5 + (-5,13)

Fx = -5,44 N
Fy = -0,13 N

Since you got both components negative your vector will be in the third quadrant.

To get the intensity (module, scalar whatever you want to call it) of that vector use:
|FR| = square root (Fx^2 + Fy^2)
Note that |FR| has an arrow above F to indicate that it's a vector, R is subscript, | | means module.

|FR| = 5,4416 N

To calculate the direction (angle ßR, resulting angle) you can use:
tg ßR = Fy/Fx
tg ßR = 0,239
ßR = 1,369°
IMPORTANT:
You must add another 180° to get correct angle, since you know your vector is in III. quadrant.

So your vector is:
FR = 5,4416 N
ßR = 181,369°

Tsk, tsk, now why would you do the lab for him? He ain't goin to leant nuttin dat way....

 

[quantumnumber]

Yes but this is an example! different numbers were used
I already took a brief look at this but I am going to take a further look at this after my precalc class. I was just studying for a physics quiz that I have today. oh, and I am a she, not a he

 

[origin]

Yes but this is an example! different numbers were used
I already took a brief look at this but I am going to take a further look at this after my precalc class. I was just studying for a physics quiz that I have today. oh, and I am a she, not a he

Sorry, young lady. I hope you excel in your Physics/Astronomy degree work!

 

[MeteorWayne]

Sorry, young lady. I hope you excel in your Physics/Astronomy degree work!

But having us do your work for you is not the way to accomplish that
Wayne

 

[Shpaget]

But I didn't do the work for her (is a girl!!! on a science forum :shock: )
I just provided formulas (which by the way can be found anywhere), and made up some numbers to show how they work.

 

[quantumnumber]

But I didn't do the work for her (is a girl!!! on a science forum :shock: )
I just provided formulas (which by the way can be found anywhere), and made up some numbers to show how they work.

Thank you very much for your help. I got it! I am like an exponential function. It takes me a while to get it, but once I understand it.....

 

[Shpaget]

You're welcome. Glad I could help.

 

[quantumnumber]

I got a 92 on my first physics test

 

[SpeedFreek]

Well done, keep up the good work!

 

[quantumnumber]

Thank you