Solving Torque Problem: Find Forces FT, Horizontal & Vertical on Beam

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The discussion revolves around calculating the forces acting on a floodlight supported by a beam and a cable. The floodlight has a mass of 40 kg, leading to a gravitational force of approximately 392.4 N. The tension in the cable, calculated to be 2056 N, helps support the floodlight while the beam experiences both horizontal and vertical forces from the pole. The user successfully calculated the horizontal force but struggles with the vertical force, concluding that it appears to be zero, which seems incorrect. Suggestions are sought for resolving the discrepancy in the vertical force calculation.
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A floodlight with a mass of 40 kg is used to
illuminate the parking lot in front of a library.
The floodlight is supported at the end of a
horizontal beam that is hinged to a vertical
pole, as shown. A cable thatmakes an angle of
11◦ with the beam is attached to the pole to
help support the floodlight. Assume the mass
of the beam is negligible when compared with
the mass of the floodlight.
The acceleration of gravity is 9.81 m/s2 .

a) Find the force FT provided by the cable.
Answer in units of N.
2056 N
b) Find the horizontal force exerted on the
beam by the pole. Answer in units of N.

c) Find the vertical force exerted on the beam
by the pole. Answer in units of N.


I got a and b but for some reason I can't get c.
My work.
Fynet=0=Tsin11+Fy-mg where Fy is the vertical force exerted on the beam by the pole.
Tsin11+Fy=mg
392.4 +Fy=392.4
Fy=0
however, that doesn't work
anyone has suggestions for part c?
 
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xregina12 said:
A floodlight with a mass of 40 kg is used to
illuminate the parking lot in front of a library.
The floodlight is supported at the end of a
horizontal beam that is hinged to a vertical
pole, as shown. A cable thatmakes an angle of
11◦ with the beam is attached to the pole to
help support the floodlight. Assume the mass
of the beam is negligible when compared with
the mass of the floodlight.
The acceleration of gravity is 9.81 m/s2 .

a) Find the force FT provided by the cable.
Answer in units of N.
2056 N
b) Find the horizontal force exerted on the
beam by the pole. Answer in units of N.

c) Find the vertical force exerted on the beam
by the pole. Answer in units of N.


I got a and b but for some reason I can't get c.
My work.
Fynet=0=Tsin11+Fy-mg where Fy is the vertical force exerted on the beam by the pole.
Tsin11+Fy=mg
392.4 +Fy=392.4
Fy=0
however, that doesn't work
anyone has suggestions for part c?

\sum\tau=\tau_1+\tau_2=r\vec{w}+r\vec{T}\rightarrow\vec{w}=-\vec{T}\sin(11\pi/180)\rightarrow\vec{T}=2057N.

Then, we notice that \sin(11\pi/180)\cdot2057=392.5 and \vec{w}=392.4. So, maybe it's just that 0.10N that they're worrying about? IDK.
 
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