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# Edexcel M3 Statics of Rigid Bodies Need help watch

1. Can anyone explain this question to me I don't really understand it. Here's the picture:
https://gyazo.com/e95b7642887c60a6e9148c4b2b684905
Can anyone explain this question to me I don't really understand it. Here's the picture:
https://gyazo.com/e95b7642887c60a6e9148c4b2b684905
Here's a diagram with some construction lines. Hopefully you can take it from there.

3. Thanks for the diagram. But how would I know if the angle alpha the slope makes with the horizontal is the same as the angle the circular base of the hemisphere makes with its centre of mass? Thank you.
Thanks for the diagram. But how would I know if the angle alpha the slope makes with the horizontal is the same as the angle the circular base of the hemisphere makes with its centre of mass? Thank you.
Not sure which angle you're refering to there - in red.

Couple of things to be aware of:

- Which lines are parallel, and
- A radius is perpendicular to the circumference of a circle.
5. Thanks alot
6. https://gyazo.com/446659a890dc2d6fc124faf1b0757b2e
How do I know when it's going to make a right-angle triangle with the plane or a non right-angle triangle?
https://gyazo.com/446659a890dc2d6fc124faf1b0757b2e
How do I know when it's going to make a right-angle triangle with the plane or a non right-angle triangle?
The image on the left is misleading, as the face of the hemisphere is not going to be vertical.

The angle OSG is going to be alpha, because SG is vertical, at right-angles to the horizontal; and SO is at right-angles to the plane, i.e. they are both (SO and the plane) turned through an angle of alpha.

The triangle on the right isn't going to be right-angled, as there is no reason why it should be. The left hand image confuses things.

Here's an update to my diagram:

angle OSG + 90 + (90-a) = 180.

Hence....
8. Thanks again. I finally understood it. M3 is such a difficult module, SHM and Statics are by far the hardest chapters.

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