81. u1 = 14 /; u2 = 7,5 /. j , , D t = 91 . , .
82. , , , v =12 /. , x 1 = 7 x 2=12 , D j = 5/6 p. = 6 . : 1) l; 2) ; 3) x 2 t = 3 .
83. , . , 1700 , 10 . .
84. 461 /. .
85. 54 / . D n = 54 . 340 /, .
86. 3,172×104 /. 
?
87. , u = 4700 / r = 8,6×103 /3.
88. , , D = 0,025 Dj = p/6?
89. , 10 , , . 340 /, 1000 .
90. 
. , , 340 , u = 340 /.
91. 
1 2, 1 2? 
, a .
92. r = 4×103 /3 = 100 . , e=0,010.
93. n =1,45 . r 0 = 5,0 0 = 50 , , r = 10,0 , h = 3 0. g, .
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94. . g = 0,023 1. = 0 L = 60 . = 50 , .
95. r 0 = 20,0 L = 30,0 . , L r = 10,0 , .
96. z= 60cos(1800 t 5,3 x), z , t , . : ) ; ) ; ) .
97. , L = 3×105 , 
2 
. , , 750 ?
98. z = A 0 g cos(w t kx), A 0,g,w k . , c h = 1,0 %, g = 0,42 1 l= 50 .
99. , 
. = 0,050 . , , , 
, .
100. = 300 . .
101. , 
, 
, 
?
102. 
, , , 
. 
.
103. 
450 . , 1 ?
104. S = 10 2 5 , E 0 = 5ּ10-5 /, H 0 = 2ּ10-4 /.
105. 0,0015 100 . .
106. 1000 . 50 . .
107. 450 360 /. , 20 .
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108. 660 / 5 . , .
109. 1,7 . .
110. 
. ν, , , .
111. 20 /. , 300 .
112. 500 / 6 . , ?
113. , n0. 20 %. u . u 330 /.
114. 
. .
115. ( ) , n0 = 130, 5 . , ? ? 340 /.
116. , = 120 / D t 0 = 5,0 . , : ) ; ) . 330 /.
117. , n0=1,8 , , 
. h= 0,8 . : ) , , ; ) , n = n0.
118. 4 e =3 . .
119. , , , . . 0,5 . e = 26, m =1, .
120. . 18,8 /. , .. , , .
