A sphere hangs suspended by a light string, resting against a vertical wall. The sphere has a mass of 2 kg and the string makes an 80° angle with the horizontal. What is the force from the wall against the ball?

(II) The two trees in Fig. 12–54 are 6.2 m apart. A backpacker is trying to lift his pack out of the reach of bears. Calculate the magnitude of the force F→ that he must exert downward to hold a 19-kg backpack so that the rope sags at its midpoint by 

(a) 1.5 m.

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(I) Three forces are applied to a tree sapling, as shown in Fig. 12–49, to stabilize it. If F→_A = 385 N and F→_B = 515 N , find F→_C in magnitude and direction.

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(II) The two trees in Fig. 12–54 are 6.2 m apart. A backpacker is trying to lift his pack out of the reach of bears. Calculate the magnitude of the force F→ that he must exert downward to hold a 19-kg backpack so that the rope sags at its midpoint by

(b) 0.15 m.

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A chandelier is supported from the ceiling by 2 chains. Both chains make a 30° angle with the vertical. The tension in each chain is the same because of symmetry:T₁=T₂=50 N. What is the mass of the chandelier?