Junior Class 1 Answered

Inakitefestival,a kite isataheight 120m& 130mstringisout . Ifthekite ,ismovinghorizontallyattherateof 5.2m/s,findtherateatwhichthestringispulledoutatthatinstant.

Asked by anjali | 20 Feb, 2017, 06:06: PM

Expert Answer

$begin mathsize 16px style L e t space t h e space t i m e space b e space t. L e t space t h e space p o s i t i o n space o f space k i t e space b e space A space a n d space p o s i t i o n space o f space s t r i n g space i s space A C. N o w comma A C squared equals A B squared plus B C squared y squared equals x squared plus 120 squared D i f f e r e n t i a t i n g space w. r. t. space t comma space 2 y fraction numerator d y over denominator d t end fraction equals 2 x fraction numerator d x over denominator d t end fraction plus 0 fraction numerator d y over denominator d t end fraction equals x over y open parentheses fraction numerator d x over denominator d t end fraction close parentheses fraction numerator d y over denominator d t end fraction x over y left parenthesis 5.2 right parenthesis space space space space space space space space space space space space space space .... left square bracket K i t e space i s space m o v i n g space a w a y space h o r i z o n t a l l y space a t space t h e space r a t e space o f space 5.2 space m divided by s e c rightwards double arrow fraction numerator d x over denominator d t end fraction equals 5.2 space m divided by s e c right square bracket W h e n space y equals 130 space m space a n d space x equals 50 space m space left square bracket u sin g space p y t h a g o r a s right square bracket fraction numerator d y over denominator d x end fraction equals 50 over 130 cross times 5.2 equals 2 space m divided by s e c end style$