# Mechanics - Statics of a particle question watch

1. Hi,

Ive been unable to answer this question -

Forces P, Q and R act on a particle at O in the plane of the co-ordinate axis Ox, Oy. Force P acts along Ox, Q acts along Oy, and R acts at angle Ѳ with Ox, in the first quadrant. Caculate the magnitude of the resultant force and the angle it makes with Ox when:

P=3N, Q=4N, R=5N, Ѳ=60 degrees

I know this is a long question and is one which is quite difficult to answer on a computer, but any time and help is greatly appreciated!

Thanks.

EDIT: sorry i posted in the wrong forum, ive posted in the maths forum instead.
2. Resolve the forces into the two components, the x-axis and the y-axis.

Resolving horizontally = Force P + RcosѲ = 3 + 5cos60 = 5.5N
Resolving vertically = Force Q + RsinѲ = 4 + 5sin60 = 8.33N

Now you've got just two perpendicular forces which allows you to use Pythagoras to work out the resultant.

Resultant force = = ~10N

To find the angle it makes with the horizontal, use Trigonometry.

Ѳ = arctan(8.33/5.5) = 56.6

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Updated: October 13, 2009
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