Question

Water is flowing continuously from a tap having an internal diameter `8xx10^(-3)`m. The water velocity as it leves the tap is `0.4 ms^(-1)`. The diameter of the water stream at a distance `2xx10^(-1)`m below the tap is close to `(g=10m//s^(2))`
A. `5.0 xx 10^(-3)` m
B. `7.5xx10^(-3)` m
C. `9.6xx10^(-3) m`
D. `3.6xx10^(-3)` m

Answer 1

Correct Answer - D
Here , `d_(1)=8xx10^(-3) m`,
`v_(1)=0.4 m s^(-1), h=0.2m`
According to equation of motion,
`v_(2)=sqrt(v_(1)^(2)+2gh)=sqrt((0.4)+2xx10xx0.2)`
`~~ 2 m s^(-1)`
According to equation of continuity, `A_(1)v_(1)=A_(2)v_(2)`
`therefore pixx((8xx10^(-3))/(2))^(2)xx0.4=pixx((d_(2))/(2))^(2)xx2`
or `d_(2)=3.6xx10^(-3) m`