chetan2u wrote:
Q.1 Assume that with the farmer’s plan the resistance from friction in the system will contribute exactly 5 vertical feet to the system’s total. For each of the following possible heights from the surface of the water source to the top of the tank, select Yes if it meets the constraints of the plan as specified. Otherwise, select No.
The constraints are the pressure in psi, which depends on vertical height and vertical height itself.
Vertical height: The vertical height is 58 feet, and it contains 5 feet of vertical height lost due to the resistance. Thus effective 53 feet.
Clearly anything above 53 feet cannot be met out of existing pump.
20 feet: <53 feet, so can be used. Let us check the pressure now. The inlet is 4 above ground and 5 feet above the water surface. Thus, pressure is 0.43psi*(20-5) = 7.95, which is less than the pressure required 10 psi.
Hence will not work...NO
40 feet: <53 feet, so can be used. Let us check the pressure now. The inlet is 4 above ground and 5 feet above the water surface. Thus, pressure is 0.43psi*(40-5) = 15.05, which is more than the pressure required 10 psi.
Will work...YES
60 feet: >53 feet, so can not be used...NO
Q.2. The farmer is considering replacing the water pump that is in place with one that has the same rating but cannot pump as many gallons per minute. For each of the following statements, select Yes if, according to the information provided, it describes a likely result of this change. Otherwise, select No.
(a) The maximum diameter of the pipe the farmer could feasibly use between the pump and the water tank would be smaller.
(b) The maximum distance between the water tank and the ground would be smaller.
(c) The maximum distance between the irrigation system inlet and the ground would be smaller.
We can safely mark NO for all as there is no link given between Pumping speed in Gallon per minute and any attribute of the pump or layout.
Q.3. Assume the farmer’s irrigation system has been completed as described. If all other specifications remain unchanged, which one of the following changes would, if made, result in an increase in the pounds per square inch (psi) at the bottom of the pipe between the water tank and the irrigation system?
The psi depends on the vertical height and increase with increase in vertical height above inlet.
Let us see which option increases the vertical height above the inlet.
(a) Increasing the height of the pump inlet....Reduces the distance between top of tank and the inlet of pump as top is fixed, resulting in decrease in vertical height above inlet
(b) Decreasing the height of the water tank....Reduces the distance between top of tank and the inlet of pump as pump inlet is fixed, resulting in decrease in vertical height above inlet
(c) Increasing the number of gallons per minute the pump pumps...No relation
(d) Decreasing the height of the irrigation system inlet....This increases the distance between top of tank and the inlet of pump as top is fixed, resulting in increase in vertical height above inlet..ANSWER
(e) Decreasing the capacity of the water tank...No change if the height remains the same. But will reduce if the same capacity is in a larger tank
I didnt get it.
Why would decreasing the height of the Irrigation System (The one on the right of the tank) affect the distance between top of the tank and inlet of pump (The one on the left side of the tank)