- #1
BridgeBuilder
- 4
- 0
First time poster, long time reader...
Consider the truss bridge as shown in the attached diagram (Each member is the same length) A force of 1000N is applied 3/4 of the way across the bridge. We get:
R1 = 250 N
R2 = 750 N
Resolving from the left we get:
T1 = 250 / sin 60
T1 sin 60 = T3 sin 60 so T1 = T3
T4 = T1 cos 60 + T3 cos 60
so T4 = T1 = T3 = 250 / sin 60
However, resolving from the right we get:
T7 = 750 / sin 60
T7 sin 60 = T5 sin 60 so T7 = T5
T4 = T5 cos 60 + T7 cos 60
so T4 = T5 = T7 = 750 / sin 60
Why do we get two different values for T4? I cannot see my mistake.
Many thanks.
Consider the truss bridge as shown in the attached diagram (Each member is the same length) A force of 1000N is applied 3/4 of the way across the bridge. We get:
R1 = 250 N
R2 = 750 N
Resolving from the left we get:
T1 = 250 / sin 60
T1 sin 60 = T3 sin 60 so T1 = T3
T4 = T1 cos 60 + T3 cos 60
so T4 = T1 = T3 = 250 / sin 60
However, resolving from the right we get:
T7 = 750 / sin 60
T7 sin 60 = T5 sin 60 so T7 = T5
T4 = T5 cos 60 + T7 cos 60
so T4 = T5 = T7 = 750 / sin 60
Why do we get two different values for T4? I cannot see my mistake.
Many thanks.