# Vector Addition Help

1. Oct 1, 2009

### VectorHugo

EDIT: ****Nevermind, I just mis-typed everything into my calculator. I had to put my X and Y values in parenthesis - ie sqrt((29.47)^2 + (-5.32)^2)**************

I *think* I am doing this right, but I can never get the right answer. Does anybody notice what is going wrong?

The correct answer to this problem is an angle of 10.2 degrees and a magnitude of 30.2 m.

1. The problem statement, all variables and given/known data

A football player runs the pattern given in the drawing by the three displacement vectors A, B, and C. The magnitudes of these vectors are A = 5.00 m, B = 15 m, and C = 18 m. Using the component method, find the magnitude and direction (theta) of the resultant vector A + B + C.

http://univirtual.info/elementaryphysics/art/images/cutnell3158c01/image_n/ngr021.gif [Broken]

2. Relevant equations

Dx: Ax + Bx + Cx
Dy: Ay + By + Cy

3. The attempt at a solution

Ax: (5 cos 90) = 0 m
Bx: (15 cos 0) = 15 m
Cx: (18 cos 325) = 14.74 m

Ay: (5 sin 90) = 5 m
By: (15 sin 0) = 0 m
Cy: (18 sin 325) = -10.32 m *i measured all the angles from the x axis*

Dx = 29.74 m
Dy = -5.32 m

D = sqrt(29.742 + -5.322) = 29.26 m

theta = tan-1 (Dy/Dx) = 10.1 degrees

Last edited by a moderator: May 4, 2017
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