physics
posted by flame on .
A horizontal pipe 17.00 cm in diameter has a smooth reduction to a pipe 8.50 cm in diameter. If the pressure of the water in the larger pipe is 8.00 104 Pa and the pressure in the smaller pipe is 6.00 104 Pa, at what rate does water flow through the pipes?

Use bernoulli's equation
p+ρV²+ρgh=constant
for each of the sections.
p=pressure
ρ=density
V=velocity
The ρgh term can be neglected if the pipe is horizontal.
The continuity equation gives
A1V1=A2V2, where
V1, V2, A1 and A2 are the velocities and cross sectional areas of the corresponding sections.
So we have two unknowns V1 and V2, and two equations
p1+ρV1²=p2+ρV2² ...(1)
V1*A1=V2*A2 ....(2)
Solve for V1 and V2. 
how do i convert the answer to kg/s

Flow is given by the product of the water velocity (m/s) and cross sectional area (m²), multiplied by the density ρ (1000 kg/m³).
or,
Q=A1*V1*ρ