Question

In the figure (see the end of this document), if the tension in the cable attaching the platform to the building on the left is 650 N, find: (a) the tension in the cable attaching the platform to the building on the right, and (b) the mass of the platform.

Answer 1

Assuming angle 30° and 45° respectively.

a.)

The horizontal component of the 650 N tension must equal the size of the horizontal component of the tension in the LEFT hand cable. If TL is the unknown tension:
650(cos 30°) = TL(cos 45°)
TL = 650(cos 30°)/cos 45° = 796 N ANS..

b.)

The weight = mg, of the platform = Σ of the two vertical components of the tensions in cables:
mg = 650(sin 30°) + 796(sin 45°) = 325 + 563 = 888N

m = 888/9.81 = 90.7 kg ANS...

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