**Draining the Swimming Pool**

William Byrne Martin Luther King

4445 S. Drexel

Chicago, Il. 60653

312-536-8680

**Objectives**:

For 9th and 10th grade

1. To determine the time needed to drain a quantity of water using tubes of

different inside diameters (I.D.)

2. To determine the time needed to drain a quantity of water using two tubes

at the same time, contrast this with the theoretical values and give

explanations for the differences.

**Materials needed**:

Stopwatch, 3 one gallon jugs, two plastic tubes about 3 feet long of

different inside diameter, plastic tray, water pails, hand calculators.

**Strategy**:

On a table place 3 one gallon jugs filled with water. Ask the class to

estimate how long it will take to drain one jug using a plastic tube of 1/4" I.D.

Show them this tube. Then, using the siphon method, drain one of the jugs using

the tube. This will be timed by someone in the class using the stopwatch. Next,

find the time according to the formula - V = (2gh)^{1/2}At. Ask someone in the Physics

department about using this formula. Find "t" using the formula. Discuss

differences from the experimental value. Go through the same process using the 1/2"

tube. Again find the experimental value and the theoretical value and discuss the

differences. Finally, using the third jug of water and both tubes, find out how

long it takes to drain the jug of water. Then compare this time with the value

given by the algebraic formula for the problem.

**Conclusions**:

Discuss differences between theory and experiment. How could the two values

be brought closer together in this experiment? Discuss the role of friction.

Return to Mathematics Index