A uniform ladder rests against a vertical wall where there is negligible friction. The bottom of the ladder rests on rough ground where there is friction. The top of the ladder is at height h above the ground and the foot of the ladder is at a distance 2a from the wall. The diagram below shows the forces which act on the ladder. Which equation is formed by taking moments?

A) Wa+Fh=2Wa
B) Fa+Wa= Fh
C) Wa+2Wa=Fh
D) Wa-2Wa=2Fh

Question

A uniform ladder rests against a vertical wall where there is negligible friction. The bottom of the ladder rests on rough ground where there is friction. The top of the ladder is at height h above the ground and the foot of the ladder is at a distance 2a from the wall. The diagram below shows the forces which act on the ladder. Which equation is formed by taking moments?

A) Wa+Fh=2Wa
B) Fa+Wa= Fh
C) Wa+2Wa=Fh 
D) Wa-2Wa=2Fh

anonymous · Answer

I am a little unsure of why answer is A?

anonymous · Answer

Any suggestions?

anonymous · Answer

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Is this how the diagram looks? 

Which point are we taking moments about?