For a given centrifugal pump, if the speed of rotation of the impeller is cut in half, how does the power required to drive the pump change

The power required to drive the pump is reduced in .

Explanation:

From Turbomachinery, we find that power required to drive the pump () is directly proportional to the cube of the speed of rotation of the impeller (). That is:

(Eq. 1)

Where is the proportionality constant.

And now we eliminate the proportionality constant by constructing the following relationship:

(Eq. 2)

If we know that , then:

The power required to drive the pump is reduced in .

  distance on the y-axis and time on the x-axis.

explanation:

the instantaneous velocity = change in position/time taken

the slope of the graph should give instantaneous velocity.

  slope of a graph = change in value of y -axis / change in values of x -axis

  comparing both the equations

    change in value of y -axis = change in position

  change in values of x -axis = time taken

so position values should be on the y axis and time values should be on the x axis.

distance on the y-axis and time on the x-axis.