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P. 3798. A 0.8 m long rod joins to a vertical axle with a bearing at its middle. The rod has negligible mass and it is frictionless. We thread point-like pierced balls of masses of 200 g on both of its ends. The two balls positioned symmetrically on both sides of the axis are linked with a thin thread of a length of 0.2 m. At the ends of the rod there are non-elastic bumpers. We spin this system with an angular velocity of 2 s-1 and then we burn the thread.

a) What path do the balls follow?

b) How much does the rod turn in 1 s after burning the fibre.

c) In what time does the rod turn by an angle of 180o?

d) What distance is done by the balls during the half turn of the rod?

e) What percentage is the mechanical loss?

(5 points)