Problem 12Problem 12

Wet towels Wet towels

Overview

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Pros

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Cons

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Problem

• When a wet towel is flicked, it may create a cracking sound like a whip. Investigate the effect. Why does a wet towel crack louder than a dry one?

Direction of discussion

• 1.Definition

• 2.Experiment

• 3.Parameters

• 4.Sound

Question on definitions

• 1.How do you define the “cracking ” sound

• 2.How do you distinguish the “cracking” sound from other sound? From frequency or from energy?

Question on experiment

Question on experiment

• 1.Is your frame rate fast enough to capture the fastest moment ?Then how long would the moment last?

• 2.How do you control the distance between the towels and recorder?

• 3.If you put a ruler and capture it from a distance, would there be some deformation?

Questions on parameters

• 1.How do you control the force when whipping towels with different weight?

• 2.Do you take the weight difference before and after whipped into consideration?

• 3. Is there some water be whipped out from the towel ?Will it affect the result?

• 4.In which circumstances will you stop

adding water to the towel?

Questions on parameters

• 5.Is there any different at the end of the towel after whipped? How do you control this part

• 6.Will the way of whipping a towel affect the sound?

• 7.Will air resistance affect the towel greatly?

• 8.A wet towel or a dry towel have greater rate of energy transformation than a dry towel? Why?

Sound

• 1.What is the origin of the ”Cracking” sound ?

• 2.Which parameter do you think contribute the most to the lager cracking sound of wet towel?

• 3.Do you think the shape of the towel end will affect the sound?

Questions for Data

• 1.How many times do you whip a towel for one data point?

• 2.Is your experiment repeatable?