Which of the following device is used to measure the rate of liquid through a pipe ?

Explanation

`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