Assignment 7 Problems(Fall Term Physics 102) 9. The diameters of the main rotor and tail rotor of a single-engine helicopter are 7.60 m and 1.02 m, respectively. The respective rotational speeds are 450 rev/min and 4 138 rev/min. Calculate the speeds of the tips of both rotors. Compare these speeds with the speed of sound, 343 m/s. V main = .522 V sound, , V rotor = .644 V sound 21. A 2 000-kg car rounds a circular turn of radius 20 m. If the road is flat and the coefficient of friction between tires and road is 0.70, how fast can the car go without skidding? V = 12 m/s 23. A 50.0-kg child stands at the rim of a merry-go-round of radius 2.00 m, rotating with an angular speed of 3.00 rad/s. (a) What is the child’s centripetal acceleration? (b) What is the minimum force between his feet and the floor of the carousel that is required to keep him in the circular path? (c) What minimum coefficient of static friction is required? Is the answer you found reasonable? In other words, is he likely to
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