The three ropes shown in the figure are tied to a steel ring. Two of the ropes are anchored to walls at right angles, and the third rope pulls as shown. If the tension in rope 2 is $110\mathrm{N}$, what is the mass of the steel ring?

A 1.5-kg block rests on top of a 7.5-kg block (Fig. 4–70). The cord and pulley have negligible mass, and there is no significant friction anywhere. <IMAGE>

(b) What is the tension in the connecting cord?

(II) One 3.2-kg paint bucket is hanging by a massless cord from another 3.2-kg paint bucket, also hanging by a massless cord, as shown in Fig. 4–41.

<IMAGE>

(b) If the two buckets are pulled upward with an acceleration of 1.45m/s² by the upper cord, calculate the tension in each cord.

(III) The double Atwood machine shown in Fig. 4–55 has frictionless, massless pulleys and cords. <IMAGE>

Determine (a) the acceleration of masses m_A,m_B ,and m_C.

(a) What minimum force F is needed to lift a piano (mass M) using the pulley apparatus shown in Fig. 4–64? <IMAGE>

(II) A 75-kg petty thief wants to escape from a third-story jail window. Unfortunately, a makeshift rope made of sheets tied together can support a mass of only 62 kg. How might the thief use this 'rope' to escape? Give a quantitative answer.