- #1

SignaturePF

- 112

- 0

## Homework Statement

19. A 1,500 Watt motor is used to pump water a vertical height of 2.0 meters out of a ﬂooded basement through a

cylindrical pipe. The water is ejected though the end of the pipe at a speed of 2.5 m/s. Ignoring friction and

assuming that all of the energy of the motor goes to the water, which of the following is the closest to the radius

of the pipe? The density of water is ρ = 1000 kg/m3

.

(A) 1/3 cm

(B) 1 cm

(C) 3 cm

(D) 10 cm ← CORRECT

(E) 30 cm

## Homework Equations

Pressure = ρgh

Bernoulli's Eq: p + ρgh + 1/2ρv^2 = Constant

Power = F dot v, Power = Work / t = dW/dT

Flow Rate Continuity:

A_0v_0 = Av

## The Attempt at a Solution

First, I said that:

A_0v_0 = pir^2*2.5

Thus, v_0 = pir^2*2.5 / A_0

Then, I used Bernoulli's Eq, but I'm confused as to how I make use of the power? I need some guidance on how to use the power in the problem or how to turn one of these equations into

one I can handle.