Water from a tap emerges vertically downwards an intial speed of 1 m/s . The cross-sectional area of the tap is `10^(-4)m^(2)` . Assume that the pressure is contant throughout the stream of water and that the flow is steady . The cross-sectional area of the steam. `0.15` m below the tap is

Options

A. `5.0xx10^(-4)m^2`
B. `1.0xx10^(-5)m^2`
C. `5.0xx10^(-5)m^2`
D. `2.0xx10^(-5)m^2`

Answer

C

Explanation

Decrease in potential energy = increasing in kinetic energy
`therefore rhogh=1/2rho(V_f^2-V_i^2)`
or `2(10)(0.15) = V_f^2 - (10)^2`
or `V_f=2ms^(-1)`
Now , from continuity equation.
`A_1V_1A_2V_1 " or " A prop 1/v`
Velocity has become two times . Hence , are of cross section will remain half .