# Thread: resultant force

1. ## resultant force

Hiya, need help with this as i dont know how to find resultant force of more than 2 forces.

Q) Forces P, Q and R act on a particle at O in the plane of the coordinate axes Ox, Oy. Force P acts along Ox, Q acts along Oy, and R acts at an angle a with Ox, in the first quadrant. Calculate magnitude of the resultant force and angle it makes with Ox.

P = 3N, Q = 4N, R = 5N, a = 60 degrees

I would really like if someone can draw diagrams too, any help will be appreciated.

thx.

2. Originally Posted by Sundae
Hiya, need help with this as i dont know how to find resultant force of more than 2 forces.

Q) Forces P, Q and R act on a particle at O in the plane of the coordinate axes Ox, Oy. Force P acts along Ox, Q acts along Oy, and R acts at an angle a with Ox, in the first quadrant. Calculate magnitude of the resultant force and angle it makes with Ox.

P = 3N, Q = 4N, R = 5N, a = 60 degrees

I would really like if someone can draw diagrams too, any help will be appreciated.

thx.
let Z = the resultant vector

$\displaystyle P_x + Q_x + R_x = Z_x$

$\displaystyle 3 + 0 + 5\cos(60) = Z_x$

$\displaystyle P_y + Q_y + R_y = Z_y$

$\displaystyle 0 + 4 + 5\sin(60) = Z_y$

$\displaystyle |Z| = \sqrt{(Z_x)^2 + (Z_y)^2}$

direction for $\displaystyle Z$ ...

$\displaystyle \theta = \arctan\left(\frac{Z_y}{Z_x}\right)$

### find the resultant force OX and OY

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