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# M1 Statics of a particle watch

1. Forces P, Q and R act on a particle at the origin O, Find the magnitude of the resultatnt force and the angle it makes with ox

a) P = 2i + 5j, Q= 3i + 4j, R = 5i + 2j
i know to find the magnitude, you just use pythag but what about the angle?

2. Well, you have found the resultant (I hope) to be 10i + 11j. So we want to find the angle between the x-axis and 10i + 11j. Let theta be the angle between them. We have a right-angled triangle whose 'opposite' side is 11, and whose 'adjacent' side is 10. So what can we say about tan theta? Hence what is theta ?

Hope this helps! Don't forget to draw a diagram ...
3. (Original post by Simba)
Well, you have found the resultant (I hope) to be 10i + 11j. So we want to find the angle between the x-axis and 10i + 11j. Let theta be the angle between them. We have a right-angled triangle whose 'opposite' side is 11, and whose 'adjacent' side is 10. So what can we say about tan theta? Hence what is theta ?

Hope this helps! Don't forget to draw a diagram ...
argh! it looks so simple when you put it like that! thanks a lot, i'vee got it now!

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