Question
Mon April 20, 2015 By: Isha Yadav

A body is thrown vertically upwards with velocity 'u'. The distance travelled by it in the fifth and sixth seconds are equal. what is the value of 'u'? (Take g=9.8m/s^2)

Expert Reply
Gajendra
Mon April 20, 2015
Distance travelled in the 5th second, PQ is given
begin mathsize 14px style PQ space equals space straight D subscript 5 space equals space straight u space plus space straight a over 2 left parenthesis 2 straight n space minus space 1 right parenthesis PQ space equals space straight u space minus space straight g over 2 left parenthesis 2 cross times 5 space minus space 1 right parenthesis space space space space space space minus negative negative negative negative left parenthesis vertical space upward space motion space of space the space body comma space straight a space equals space minus straight g right parenthesis rightwards arrow PQ space equals space space straight u space minus space fraction numerator 9 straight g over denominator 2 end fraction space space minus negative negative negative negative left parenthesis eqn. space 1 right parenthesis Now space the space distance space QP space is space given space as colon QP space equals space ut space plus space 1 half gt squared QP space equals space 0 space plus space 1 half straight g left parenthesis 1 right parenthesis squared space rightwards arrow QP space equals space straight g over 2 space space space space minus negative negative negative negative space left parenthesis eqn.2 right parenthesis Now comma space PQ space equals space QP So space from space eqn space left parenthesis 1 right parenthesis space and space left parenthesis 2 right parenthesis space we space get colon space space straight u space minus space fraction numerator 9 straight g over denominator 2 end fraction space equals space straight g over 2 straight u space equals space 5 straight g space equals space 5 cross times space 9.8 space equals space 49 space straight m divided by straight s rightwards arrow straight u space equals space 49 space straight m divided by straight s end style
Mon April 10, 2017

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