Resolving vectors is the process of turning a vector into two perpendicular components, which allows vectors to be added together when they are at any angle to each other.
Definitions
Key word
Definition
Vector
A quantity that has both a magnitude and a direction
Resolving a vector
Splitting a vector into two perpendicular components
Equations
description
equation
Horizontal component of a vector
Fx=Fcosθ
Vertical component of a vector
Fy=Fsinθ
Resolving a vector
The two components of any vector is given by the following two equations.
Fx=Fcosθ
Fy=Fsinθ
where Fx and Fy are the horizontal and vertical components of the vector respectively, F is the magnitude of the vector and θ is the angle the vector makes with the horizontal.
1.
Hypotenuse - F
2.
Opposite - Fy
3.
Adjacent - Fx
This graphic shows the locations of Fx, Fy and F on a triangle. The trigonometric ratios relating the lengths and angles of a triangle are as follows.
sinθ=hypotenuseopposite
cosθ=hypotenuseadjacent
tanθ=adjacentopposite
Substituting in Fx, Fy and F for the adjacent, opposite and hypotenuse of a triangle then rearranging the equations will give the equations for the components of a vector.
Example
A force of magnitude 10N acts at 60° to the horizontal. Calculate the horizontal and vertical components.
First, write down the equations.
Fx=Fcosθ
Fy=Fsinθ
Next, substitute in the values.
Fx=10×cos60
Fx=5N
Fy=Fsinθ
Fy=8.66N
The horizontal component is 5N and the vertical component is 8.66N.
Adding non-perpendicular vectors
In order to add vectors that are not perpendicular to each other, the vectors must first be resolved into their components. Then, the total magnitudes in the horizontal and vertical directions are calculated. Finally, the components can be combined using Pythagoras' theorem to find the final magnitude and direction of the resultant.
Example
Calculate the resultant of the following two forces.
First, write down the equations to resolve the forces.
Fx=Fcosθ
Fy=Fsinθ
Next, substitute in the values.
Fx=10×cos45
Fx=7.1N
Fy=10×sin45
Fy=7.1N
Next, sum the horizontal and vertical forces.
Rx=6+7.07
Rx=13.1N
Ry=7.1N
Next, use Pythagoras' theorem to calculate the resultant force.
R=7.12+13.12
R=14.9N
Finally, use trigonometry to calculate the resultant force's direction.
tanθ=adjopp
tanθ=13.077.07
θ=28.4°
The resultant force has a magnitude of 14.9N and a direction of 28.4°.
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Resolving forces
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FAQs - Frequently Asked Questions
How do you add non-perpendicular vectors?
In order to add vectors that are not perpendicular to each other, the vectors must first be resolved into their components.
What is resolving a vector?
Resolving a vector is separating a vector into horizontal and vertical components.
What is a vector?
A vector is a quantity with both magnitude and direction.