A purple beam is hinged to a wall to hold up a blue sign. The beam has a mass of
ID: 2094949 • Letter: A
Question
A purple beam is hinged to a wall to hold up a blue sign. The beam has a mass of mb = 6.2 kg and the sign has a mass of ms = 17.2 kg. The length of the beam is L = 2.52 m. The sign is attached at the very end of the beam, but the horizontal wire holding up the beam is attached 2/3 of the way to the end of the beam. The angle the wire makes with the beam is ? = 33.8 1.What is the tension in the wire? 2What is the net force the hinge exerts on the beam?
3.The maximum tension the wire can have without breaking is T = 861 N.What is the maximum mass sign that can be hung from the beam?
Explanation / Answer
1.
balancing moment about hinge point ,
Tsin33.8 x 2L/3 = 6.2gcos33.8 x L/2 + 17.2gcos33.8 x L
T = 165.72 x 3/2sin33.8 = 446.86 N
2.
balancing forces in x
T = Hx
Hx = 446.86 N
balancing forces in y
mg + Mg = Hy
Hy = 23.4*9.8 = 229.32 N
net hinge force = sqrt ( Hy^2 + Hx^2) = 502.2 N
3
.Tsin33.8 x 2L/3 = 6.2gcos33.8 x L/2 + mgcos33.8 x L
here T is 861 N , so we have to find out m
861sin33.8 x 2L/3 = 6.2gcos33.8 x L/2 + mgcos33.8 x L
319.31 = 25.27 + 8.15m
m = 36.08 kg