- #1
pooker
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Homework Statement
We were given six homework assignments for lab. We were required to find the force and angle through three given experiments.
1. Experimental using a force table
2. Graphically using head to tail, etc
3. Analytical using basic means to find the answers
Homework Equations
I have two problems
1st problem
Vector resolution
F1 = (.1)gN theta = 30
F2 (.2)gN theta = 90
F3 (.3)gN theta = 225
2nd Problem
Vector resolution
F = (.3)gN theta = 60
Find fx and Fy
Find graphical answer, analytical answer and Experimental answer for each
The Attempt at a Solution
1st Problem attempt at solution
Using the force table I got F = (.130)gN Theta = 150
Using Graphical I got F = (.131)gN theta = 162
Now my problem is with analytical
I used these equations
Rx = Rcostheta
Ry = Rsintheta
r = sqrt(rx^2 + ry^2)
theta = arctan rx/ry
rx = .1cos30 + .2cos90 + .3cos225 = -.1255
ry = .1sin30 + .2sin90 + .3sin225 = .038
R = sqrt( -.1255^2 + .038^2) = .131
Theta = arctan .038/-.1255
Theta = 343.2 ? It seems grossly off. I feel like I am forgetting something, but our book does not even really cover three vectors. I had to look online for how to do it.
2nd problem attempt
Using force table
Fx = .140gN
Fy = .245 gN
Using graphical (I plotted this like a 90 degree triangle
Fx = .16gN
Fy = .25gN
Using analytical
I know c^2 = a^2 + b^2 so .9 = a^2 + b^2
b / sintheta = R / sin Y
sin theta is the angle R casts onto A which equals 60
Sin Y is the angle sides B and A make
b / sin60 = .3/sin90
b / .866 = .3
b = .866(.3) = .2598
so Fy = .2598
.9 = .2598^2 + a^2
.9 = .0675 + a^2
.8325 = a^2 = .91
so Fx = .91 ? Why is it so low as compared to the graphical and experimental? I feel something is off. All of my other calculations were pretty dead on .