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A gardener is watering plants at the rate 0.1 litre/sec using a pipe of cross-section 1 cm_2. What additional force he has to exert if he desires to increase the rate of watering two times ? |
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Answer» Solution :`F= Adv^(2) =((Av)^(2)d)/A`If rate of WATERING plant (Av) is doubled, it means AMOUNT of water poured /sec is doubled which is possible only if velocity is doubled. Hence force is to be made 4 times. `therefore`additional force = 3 times initial force `=3Adv^(2) =3(Av)^(2)/A d = (3 XX 0.1 xx 0.1 xx 10^(3))/10^(-4) = 3 xx 10^(5)` N |
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