# Physics

posted by .

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?

Can someone tell me what equations to use or how to approach this because I have no idea.

• Physics -

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 -

GOOD GOD, that was something.

## Similar Questions

1. ### Physics

Hi can someone advise whether my methodology is right on this with a potential energy of 589 kJ per tonne, 100 tonnes of water per second are delivered to a turbine. Assuming all the potential energy of this water is used to drive …
2. ### Physics - Angular Momentum

Water drives a waterwheel (or turbine) of radius 3.5 m. The water enters at a speed v_1 = 7.5 m/s and exits from the waterwheel at a speed v_2 = 4.0 m/s. a) If 84 kg of water passes through per second, what is the net torque?
3. ### Maths

Calculate the number of litres of water delivered per minute by a pipe with cross-sectional area 15 square centimetres, if the water passes through the pipe at an average speed of 30cm/s (second) P.S. Working out please
4. ### physics

Starting from rest at the top, a child slides down the water slide at a swimming pool and enters the water at a final speed of 4.00 m/s. At what final speed would the child enter the water if the water slide were twice as high?
5. ### Physics

A 67.0 kg person, standing on a diving board, dives straight down into the water. Just before striking the water, her speed is 5.50 m/s. At a time of 1.75 s after she enters the water, her speed is reduced to 1.10 m/s. What is the …
6. ### Physics

Suppose there is a small hole (radius=0.0203) at the base of a large tank. If the height of water in the tank is 15m (a) what is the speed of water escaping through the hole?
7. ### Math - Calculus

Water is flowing in a cylindrical pipe of radius 1 inch. Because water is viscous and sticks to the pipe, the rate of flow varies with distance from the center. The speed of the water at distance r inches from the center is 10(1-(r^2)) …
8. ### Physics

A sound wave is incident on a pool of fresh water. The sound enters the water perpendicularly and travels a distance of 0.55 m before striking a 0.10-m-thick copper block lying on the bottom. The sound passes through the block, reflects …
9. ### physics again

A Chinook salmon has a maximum underwater speed of 3.58 m/s, but it can jump out of water with a speed of 6.26 m/s. To move upstream past a waterfall, the salmon does not need to jump to the top of the fall, but only to a point in …
10. ### Physics

Water flows from a fire truck through a hose that is 11.7 cm in diameter and has a nozzle that is 2.0 cm in diameter. The firemen stand on a hill 5.0 m above the level of the truck. When the water leaves the nozzle, it has a speed …

More Similar Questions