a particle travels a distance of 20 metres in 7th seconds and 24 metres in 9 th seconds how much distance it should be travel in 15th second
 
 
First write formula

Asked by Sudhanshu Shridhar | 30th May, 2015, 04:20: AM

Expert Answer:

begin mathsize 12px style Let space straight u space abd space straight a space be space the space intial space veleocity space and space unifrom space acceleration space of space the space body. Distance space travelled space in space 7 th space seconds comma space straight D subscript 7 space equals 20 straight m Distance space travelled space in space 9 th space seconds comma space straight D subscript 9 space equals 24 straight m Formula space is space given space as comma straight D subscript straight n equals straight u plus straight a over 2 open parentheses 2 straight n minus 1 close parentheses therefore space straight D subscript 7 equals straight u plus straight a over 2 open parentheses 2 cross times 7 minus 1 close parentheses rightwards double arrow 20 equals straight u plus 13 over 2 straight a space space space space space space space space space space left parenthesis straight i right parenthesis straight D subscript 9 equals straight u plus straight a over 2 open parentheses 2 cross times 9 minus 1 close parentheses 24 equals straight u plus 17 over 2 straight a space space space space space space space space space left parenthesis ii right parenthesis Substracting space left parenthesis ii right parenthesis space from space left parenthesis straight i right parenthesis comma space we space get 4 equals 2 straight a therefore straight a equals 2 space straight m divided by straight s squared Substituting space in space eq left parenthesis straight i right parenthesis space we space get comma 20 equals straight u plus 13 over 2 cross times 2 equals straight u plus 13 plus straight u equals 20 minus 13 equals 7 space straight m divided by straight s squared straight D subscript 15 equals straight u plus straight a over 2 open parentheses 2 cross times 15 minus 1 close parentheses therefore 7 plus 2 over 2 cross times 29 equals 36 space straight m space Distance space travel space in space 15 th space second space is space 36 space straight m end style

Answered by Priyanka Kumbhar | 1st Jun, 2015, 09:34: AM

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