Thread: mechanics help (moments)

I am stuck on question 4b, if anyone can have a look at my attachment and help ?

I keep getting a negative answer. Here's my working;

the reactions at point Q and R =




so the reaction at point q = 80g and reaction at point r = 40g, is this bit correct?


taking moments about 'Q'

is this moments equation correct? cause when I solve for 'xm' it gives me -0.26 ?

Hello Tweety

Originally Posted by Tweety

the reactions at point Q and R =




so the reaction at point q = 80g and reaction at point r = 40g, is this bit correct?

Yes

Originally Posted by Tweety

taking moments about 'Q'

is this moments equation correct? cause when I solve for 'xm' it gives me -0.26 ?

No, it's not. I assume that is the distance QX? If so, then the term in your equation should simply be . Leave the weight of Arthur as , and you get:







So QX is 1.07 m.

Grandad