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Stuck on M2 moments

Question attached. For a), I called tension on string BC Ta and tension in D and the mass Tb.

Resolve upwards:
Tasinα+Tb=600

Moment around a):
400(2)+200(3)=Tasinα(4)+Tb(3)
Which leads to Ta=400root5 when solving simultaneously

Where have I gone wrong?

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Reply 1

TeeEm

Original post by bobbricks

I get 400(2)+200(3) = 4Tsina by taking moments about the hinge

then resolving

Verically
Y+Tsina = 600

Horizontally
X=Tcosa

where X and Y are the components of reaction at the hinge

(edited 9 years ago)

Reply 2

SherlockHolmes

Original post by TeeEm

I get 400(1.5)+200(2) = 3Tsina by taking moments about the hinge

I think this should be 400(2) + 200(3) = 4Tsina.

Reply 3

TeeEm

Original post by SherlockHolmes

I think this should be 400(2) + 200(3) = 4Tsina.

possibly
i might have misread distances

teaching at the moment and I have no glasses!...

Reply 4

bobbricks

Original post by TeeEm

I get 400(2)+200(3) = 4Tsina by taking moments about the hinge

then resolving

Verically
Y+Tsina = 600

Horizontally
X=Tcosa

where X and Y are the components of reaction at the hinge