(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A plank of wood is lifted off the ground so it has one side on the ground (A) and the rest of the wood at a slope at 15degrees to the horizontal. The length of the wood (AC) is 2.5m. A force is applied at C at 65degrees to the horizontal to the left keeping it in equilibrium. The mass of the wood is 90g and the centre of mass is at B (this was 1.875m from A when the wood was flat, so presuming that it is at the same point?). Show that the lifting force is 649N

2. Relevant equations

Moment= Force x Perpendicular distance

Total clockwise moments=total anticlockwise

3. The attempt at a solution

Well i've tried taking moments about A so:

Fsin65 x 2.5 = 90gsin15x1.875

But this doesnt give the right answer.

Do I need to consider the reaction force at A? Or friction?

Any help at all would be greatly appreciated. Many thanks.

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# Homework Help: Mechanics question involving moments

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