Falling Water
Falling water contains energy that can be used to do work. This energy is called waterpower.
Waterpower depends on:
- HEAD (drop or fall of water in feet) and
- FLOW (quantity or amount of water in cubic feet per second)
Waterpower = Head x weight of water x flow
We assume the weight of water remains the same. Changes in waterpower will directly related to changes in head and flow.
Compare the Power
- If two mills have the same head and the same flow, would you expect the power generated to be the same or different? Explain why.
- The falls (head) in Waltham are 8 ft. high. in Lowell the falls are 32 ft. high. If the flow in both rivers were the same, which would have more power? How much more?
- The flow at my mill is 300 cusecs (cubic ft./sec). The flow at your mill is 900 cusecs. The head at both are the same. How will your power compare to mine?
- They will be the same.
- Mine will be 3 times as much as yours.
- Yours will have 3 times as much as mine will.
- Yours will have twice as much power as mine.
- John's Mill had a head of 20 ft. and a flow of 210 cusecs. Mary's mill has a head of 15 ft. and a flow of 280 cusecs Whose mill will have more power? How much more power? Horse power is a measure of energy equal to the amount of work that can be done by a horse. 1 Horse Power (HP) = 550 ft.lbs/sec
- Mills A and B have the same flow. The head at A is 13 ft and at B is 17 ft. Show how much more power B will produce in a fraction. Suppose Mill A produces 260 HP. How much will Mill B produce? If Mill B produced 850 HP, what would Mill A produce?
- At Mill A, flow increases to 450 cusecs while at B it will be at 350 cusecs. If Mill B produces 2340 HP, how much will A produce?
