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This page shows questions in the Waterwheel public release module at MSDE. Life Science MISA
"Waterwheel"

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Expand All Official Practice Test

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Hydroelectric Station

The Deep Creek Hydroelectric Station is located in Garrett County, Maryland. It has two turbines that drive generators to produce 20 megawatts (MW) of electricity. The dam built for this hydroelectric station formed Deep Creek Lake.

The description and model shows how a typical hydroelectric station works.

  • Water enters the penstock, a large pipe running from the reservoir above the dam to the turbines near the base.
  • At the end of the penstock, the water turns the turbine, a wheel or rotor with blades.
  • The turbine is connected to a generator, which has several electromagnets inside many coils of copper wire.
  • When the water spins the turbine, the moving electromagnets within the generator produce electricity.
  • The transformer sends the electricity to the power station.
  • The water flows out of the penstock and turbine at the tailrace.
A diagram titled, Hydroelectric Station Model. A reservoir is shown at the left with water flow in a penstock coming from the reservoir, through a dam, and into a turbine. A transformer is connected to a generator that is connected to the turbine. Water at the right is labeled Tailrace.

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Downspout Generator

Students use the hydroelectric station model to build a downspout hydroelectric generator. A downspout is a pipe that carries rainwater down from a roof or rain gutter. Using materials from a local hardware store, the students build the waterwheel prototype shown.

The diagram titled Downspout Waterwheel shows a roof line with a rain gutter and downspout. Water pours through the downspout to a waterwheel that is connected to a generator.

The waterwheel prototype uses rain as its source of water.

  • Rainwater falling on the roof collects in the rain gutter and flows into the downspout.
  • Rainwater in the downspout flows into the containers attached to the waterwheel, making the waterwheel turn.
  • The greater the volume of rainwater flowing into the container, the faster the waterwheel turns.
  • As the waterwheel spins, it rotates the shaft attached to the electromagnets producing electricity.

The students gathered information on the average yearly rainfall for several states.

There is a table titled Annual Precipitation. The table has three columns and six rows. The first column heading is State. The second column heading is Average Yearly Rainfall in millimeters. The third column heading is Average Number of Rain Days per Year. The first row is Florida, one thousand five hundred seventy-two, one hundred twenty-eight. The second row is Maryland, one thousand one hundred thirty-one, one hundred eleven. The third row is Nevada, two hundred forty-four, thirteen. The fourth row is Texas, one thousand one hundred fifty, one hundred six. The fifth row is Utah, three hundred ten, ninety-four. The sixth row is Washington, nine hundred forty-three, one hundred forty-seven.

The students researched data on the flow rates of water based on the amounts of rainfall, the roof area drained, and the distance between the roof and the waterwheel. The flow rate is the rate at which water is falling from the roof onto the waterwheel. The students calculated the estimated power Pea in watts (W) of the waterwheel by using the formula P equals rho Q G H eta where

Density of water rho = 1000 kg/m³

Flow rate Queue = Rate of water flowing in the downspout (penstock) in m³/s

Acceleration due to gravity Gee = 9.81 m/s²

Height Aich = Change in the height of water in m

Efficiency Eta = Efficiency of the system

The students predicted the performance of a downspout waterwheel from a roof height of 5 m with different flow rates, and assuming 100% efficiency. The table shows the data calculated by students.

There is a table titled Calculated Downspout Power Generation. The table has two columns and four rows. The first column heading is Downspout Flow Rates in cubic meters per second. The second column heading is Power Generation in watts. The first row is five point eight times ten to the negative three, two hundred eighty-four point five. The second row is four point seven times ten to the negative three, two hundred thirty point five. The third row is three point one five times ten to the negative three, one hundred fifty-four point five. The fourth row is one point six times ten to the negative three, seventy-eight point five.

To check if the waterwheel generator was producing enough power to run a small household appliance, the students connected an incandescent light bulb to the generator.

There is a table titled Effect of Flow Rate on Light Bulb. The table has three columns and four rows. The first column heading is Downspout Flow Rates in cubic meters per second. The second column heading is Power Generation in watts. The third column heading is Effect on Light Bulb. The first row is eight point three times ten to the negative four, thirty point five, no light. The second row is one point six seven times ten to the negative three, sixty-one point four, no light. The third row is two point five times ten to the negative three, ninety-two point zero, flickering yellow light. The fourth row is four point one times ten to the negative three, one hundred fifty point eight, dim yellow light.

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Select the phrases that best show the inputs and outputs of the turbines in a hydroelectric station while the turbines are in motion, and drag them into the appropriate boxes. Each phrase can be used once.

Two boxes are shown. The left box is titled, Energy inputs. The right box is titled, Energy outputs. Five elements are shown below the boxes that can be selected and placed in one of the boxes. The elements are labeled, Kinetic energy of water, Electrical energy, Thermal energy, Gravitational potential energy of water, and Sound energy.

This is a multiple choice question that allows you to select only one option.

Different hydroelectric stations have different distances between their reservoirs and their tailraces.

Which statement best describes how the power generated from a hydroelectric station with a greater distance between its reservoir and tailrace compares to the power generated from Deep Creek Hydroelectric Station?

  1. A.
    The power output is less due to less initial kinetic energy.
  2. B.
    The power output is less due to less initial gravitational potential energy.
  3. C.
    The power output is greater due to greater initial kinetic energy.
  4. D.
    The power output is greater due to greater initial gravitational potential energy.

This is a question with 3 parts, including a question with drop-down menus from which you must select an option to fill in the blank.

Select the words that best complete the statements to demonstrate how energy is transformed by the downspout waterwheel prototype.

Rainwater on the roof has  
  energy, which is converted to  
  energy when it flows to the downspout and spins the waterwheel. As the waterwheel spins, the generator converts the energy to  
  energy.

This is a multiple choice question that allows you to select only one option.

The students want to power a fan that uses 350,000 W of electricity. At what distance below the roof would the waterwheel prototype have to sit in order to generate enough power when the flow rate is 5.0 m³/s, assuming the efficiency of the system is 100%?

  1. A.
    5.0 m
  2. B.
    7.1 m
  3. C.
    9.5 m
  4. D.
    350 m

This is a test question that allows you to enter extended text in your response.

Use evidence from the waterwheel prototype to explain how the performance of the prototype could be improved. Be sure to note any trade-offs in the suggested modifications.