| BETA : Translation : Forces 02 : Resultant Force Vector : Beta Physics Homework Game
Description : Resultant force vector from the sum of two force vectors.
Discussion : In order to add two force vectors Fa and Fb, they must first be converted into cartesian values which are summed to find the resultant force cartesian values Fx and Fy. Fx and Fy can then be converted back into the resultant vector. See Figure Resultant Force Vector
Fx = Fa * cosd(θa) + Fb * cosd(θb)
Fy = Fa * sind(θa) + Fb * sind(θb)
Fr = √(Fx2 + Fy2)
θr = atan2d(Fy, Fx)
To convert from Fr and θr back to Fb and θb
Fx = Fr * cosd(θr)
Fy = Fr * sind(θr)
define custom variables
Fbx = Fx - Fa * cosd(θa)
Fby = Fy - Fa * sind(θa)
Vector Fb
Fb = √(Fbx2 + Fby2)
θb = atan2d(Fby, Fbx)
For the special case where θr = 0 and θa and θb are known, find Fb and Fa
Fx = Fr
Fy = 0
define custom variable
aox = -sind(θb) / sind(θa)
Vectors Fb and Fa
Fb = Fr / (aob * cosd(θa) + cosd(θb)
Fa = aob * Fb
where
Fa Fb and Fr = force amplitudes
θa θb θr = force angles
Fx and Fy = cartesian values of resultant force vetor
Fbx Fby = cartesian values of vector Fb
aob = ratio of Fa / Fb
Note : To find Fa and Fb from Fr where θr ≠ 0. Rotate all of the vectors by -θr so that θr = 0;. The angles are in degrees. You are recommended to use the trigonometry degree functions sind(), cosd(), and asind().
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