Don't Be A Drag

Research Questions

• What causes drag?
• Does the shape of something affect drag?

Some objects move through air and water more easily. Shape is one factor that reduces friction and drag in the water.

Materials:

• scale
• ball, block, and plate similar in weight
• fishing line
• spring scale
• scissors
• pool
• paper
• pencil

Experimental Procedure:

1. Gather the necessary materials. Use the scale to make sure that the ball, block, and plate being used are similar in weight.
2. Wrap fishing line around each object. Leave the same length of line for each object.
3. The line should be long enough for the object to reach the pool as you walk along the edge (about 3 – 4 feet).
4. Attach one of the items to the spring scale. Lower the item in the water and walk from one end of the pool to the other. Note the reading on the spring scale and record it.
5. Repeat this step 5 times to get an average. To average, add each reading of the spring scale and divide by 5.
6. Repeat step 3 with the remaining two items. Be sure that you are walking the distance of the pool at the same rate of speed and that each item is lowered into the water at approximately the same depth.
7. Compare the results and draw a conclusion.

Terms/Concepts: drag: a force that slows something down friction: drag; a force that slows something down resistance: the opposite reaction to a force; Shape is one factor that reduces friction and drag and allows for something to move more easily through water.

References:

“Friction: Slowing things down” at http://www.darvill.clara.net/enforcemot/friction.htm “What is Friction?” at http://www.fearofphysics.com/Friction/frintro.html “Resistive Force of Friction” by Ron Kurtus at http://www.school-for-champions.com/science/friction.htm