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One end of a 2m long beam is lifted up with a piece of rope until the beam is 30 degrees respect to the ground with the other end resting on the ground. Assume that the rope is vertical. How much the beam weighs if the weight measured at the beam end of the rope is 20kg?

2006-11-08 01:58:51 · 2 answers · asked by Gabor S 2 in Science & Mathematics Physics

2 answers

sin 30= weight at end/ actual weight
actual weight = 20/ sin 30
= 40

2006-11-08 02:08:12 · answer #1 · answered by wineasy03 6 · 0 1

40 kg
the rope is vertical so there is no friction force from the ground:(force balance at the horizontal direction)

torque balance( with respect to rope joint position):
w * 1/2 L cos 30 = F * L cos 30
w=2F=40 kgf

L=length of beam

2006-11-08 10:01:40 · answer #2 · answered by Ormoz 3 · 0 0

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