Two neighbors communicate with a homemade string phone (Fig. P12.68). The simple phone consists of two ends of a string (total mass of 18 g) attached to the bottom of two paper cups. The string is stretched between the two homes at a tension of 10 N over the distance of 35 m.

(a) How long does it take communication to travel on the string from one home to the other?

(b) How long would it take to communicate by yelling out the window??

(c) How long would it take to communicate over cell phones if the nearest cell tower is 5.5 km away? (Consider only the propagation time of the radio waves and assume that the call is already connected.)

Figure P12.68

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