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# Mechanics 1B AS Angles watch

1. Ok, I understand how to calculate all of the angles and forces quite well, I could easily pass that. What I don't quite understand is how to figure out the angles on an inclined plane after drawing the model. I draw the model as a sketch to help and add on all the necessary forces but after that o can't figure out the correct angles to use. Any help would be very much appreciated because I'm teaching myself this and don't have anyone else to ask. Thanks
2. I'm not quite sure what you're asking. What angles are you having difficulty finding?
3. usually true,

parallel to slope mainly sin (theta)
perpendicular to slope cos (theta)

I would still recommend drawing the triangles on the diagram
4. Draw the triangles is always the best way.

One method I picked up is whether or not you want the majority of the force - in a hypothetical example, where the angle of the plane, , to the horizontal the weight of an object is mostly acting into the slope, perpendicular to it. As, when theta is less than 45 degrees, , we want the larger and thus the cosine of the angle, so the component of the weight perpendicular to the slope is .

That probably wasn't very clear, but I hope you get my drift.

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