Sketch the doppler effect from the driver's position

Ok i am attempting to my niece attach a galvanized wire (like a tether for a dog) at the corner of two fences, making a tightwire if you will and we drilled a hole in a softball and she hits it. the ? and problem is that we can not get the wire taunt enough where it doesnt sag after hitting the ball once, and the wire sags and wobbbles. its a 15 ft rubber covered galvanized wire and one can adjust the length of the placing of the wire by having it make the corner of 2 fences become a it can be adjusted, however, with all our human strength and pliers we could not make it taunt as possible. is there anything other that attaching it to a car to do this. sorry abt the length but it would mean the world to my niece if i could solve this came up with the entire idea herself, and she is 14 and paid for the wire and did as much work as i did drilling a hole through a softball wide enough for attaching piece at each end of the wire that clips on to the fence. . any ideas welcome if serious. but awesome if it is a fact. much obliged. bucky bukowski buckman

Electric charge is uniformly distributed inside a nonconducting sphere of radius 0.30 m. the electric field at a point p, which is 0.50 m from the center of the sphere, is 15,000 n/c and is directed radially outward. what is the maximum magnitude of the electric field due to this sphere

When using two-wire cable to feed a 240-v appliance that does not require a neutral wire, you should a. mark both ends of the white wire green. b. use the cable as is. c. use only the black wire. d. mark both ends and any exposed area of the white wire black.