Posted by Odd on Sunday, April 13, 2008 at 12:35am.
Water drives a waterwheel (or turbine) of radius 3.0m. The water enters at a speed of v1 = 7.0 m/s and leaves at a speed of v2= 3.0 m/s.
A) if 150kg of water passes through per second, what is the rate at which the water delivers angular momentum to the waterwheel? [answer: 1800 kg m^2/s^2]
B) what is the torque the water applies to the waterwheel? [answer: 1800 m N]
C)If the water causes the waterwheel to make on revolution every 5.5 s, how much power is delivered to the wheel?
[answer: 2100 w]
Can someone tell me what equations to use or how to approach this because I have no idea.

Physics  drwls, Sunday, April 13, 2008 at 1:02am
A and B are really asking the same question, and the results are the same, since 1 N = 1 kg m/s^2.
Assume that the water enters and leaves the waterwheel tangent to the wheel. The loss of angular momentum of the water, measured about the axis of the wheel, equals the TORQUE imparted to the wheel. The water wheel is probably NOT, in steady state, gaining angular momentum due to the action of the water; the water is instead overcoming friction or an electrical generaltor torque.
Ther torque provided by the water is
(mass flow rate)*(change in V)*R
= 150 kg/s* 4 m/s * 3.0 = 1800 N m
C) Power = Torque*(angular velocity)
= 1800 M n* (2 pi rad/5.5 s) = 2056 W.
They want you to use only two significant figures, so that is why they say the answer is 2100 W.

Physics  Anonymous, Sunday, April 13, 2008 at 1:05am
GOOD GOD, that was something.
Answer This Question
Related Questions
 Physics  Angular Momentum  Water drives a waterwheel (or turbine) of radius 3....
 Physics  A sound wave is incident on a pool of fresh water. The sound enters ...
 physics again  A Chinook salmon has a maximum underwater speed of 3.58 m/s, but...
 Physics  A 67.0 kg person, standing on a diving board, dives straight down into...
 Physics  Hi can someone advise whether my methodology is right on this with a ...
 Physics  Suppose there is a small hole (radius=0.0203) at the base of a large ...
 Math  Calculus  Water is flowing in a cylindrical pipe of radius 1 inch. ...
 physics  Starting from rest at the top, a child slides down the water slide at ...
 Maths  Calculate the number of litres of water delivered per minute by a pipe ...
 Physics  If a salmon swims straight upward in the water fast enough to break ...
More Related Questions