Name: Joe Martin and Katie Herman
PHS 381L  Biomechanics
FORCES/VECTOR ADDITION
Learning objectives:
To increase understanding of vectors. This includes 1)how to convert rectangular
coordinates (x,y) to polar coordinates (resultant magnitude and angle) 2) how to add vectors that are
not all vertical and horizontal, 3) to increase understanding of the effects of muscle fiber angles in
penniform muscles and 4) to understand vector resolution of forces and vector composition of
forces.
Equipment:
calculator
To get full credit on each of the questions you must

Show (explain) all of the steps you perform

and you must show your calculations.

Explanation must be complete.

Additionally you must ‘draw’ the vectors you are adding as well as the ones
you calculate as your answer.
For example if I need to convert (100N, 100N) into polar coordinates my
calculations and answer would look like this:
A
2
+B
2
=C
2
100
2
+ 100
2
= C
2
C = 141.4 N
Answer: 141.4N at 45 degrees
Θ=Tan
1
opp/adj
Θ=Tan
1
100/100
Θ=45˚
I did this example on Microsoft word in just a few minutes. You can ‘Insert symbols’
to add Θ and ˚, and you can use superscript (formatfont, if you use Microsoft
word) to make numbers squared like Tan
1
and A
2
+B
2
=C
2
. If you’d just rather
copy those from here and past them into your solutions below feel free.
Draw
the arrows like the ones above to show me which direction your vectors are
directed.
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View Full DocumentPHS 381 – Biodynamics Lab
Name _______________________________________________
Introduction/Procedure:
When converting polar and rectangular coordinates remember that with
rectangular coordinates (x,y) positive numbers are directed up or to the right and negative numbers
down or to the left. This holds true for all vertical and horizontal vectors but not vectors that are not
vertical or horizontal. Vectors that are not either horizontal or vertical are given a positive
magnitude and also a direction. The direction is typically reported as an angle from horizontal, for
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 Summer '11
 STAFF
 Force, net force, Achilles Tendon, Biodynamics Lab

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