Let’s InvestigateLet’s Investigate

Great white shark ‘Jaws’

An object that is streamlined will move faster

through water than an object that is not streamlined

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Testing a HypothesisTesting a HypothesisHypothesis: An object that is streamlined will move faster through

water than an object that is not streamlined.

Materials: Blu-Tack, tall measuring cylinder & stopwatch

1. Discuss the hypothesis with the other members of your team.

2. Identify the variables (see slides 6 and 7).

3. Draw up an experimental plan.

4. Design a chart on which to record the data you collect.

5. Carry out investigation (Remember you may have to modify your

original plan.)

6. Write an account of the investigation into your copybook,

explaining your method and describing your results and

conclusions.

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Independent VariableIndependent Variable

Dependent VariableDependent Variable

Fixed Variables/Fixed Variables/

ConstantsConstants

Replicates - Number of Replicates - Number of times each shape was times each shape was testedtested

© Sheila Porter – www.scifest.ie

Complete the ChartComplete the Chart

Complete the ChartComplete the Chart

Independent VariableIndependent Variable

Dependent VariableDependent Variable

Fixed Variables/Fixed Variables/

ConstantsConstants

Replicates - Number of Replicates - Number of times each shape was times each shape was testedtested

Shape

Time taken to travel distance/speed

1. Mass of object 2. Distance/Height of water 3. Height of drop

ThreeThree

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Sample Table of ResultsSample Table of ResultsShapeShape Trial 1Trial 1

Time Time (s)(s)

Trial 2Trial 2

Time Time (s)(s)

Trial 3Trial 3

Time Time (s)(s)

AverageAverage

Time (s)Time (s)DistanceDistance

cmcmSpeedSpeed

cm/scm/s

112233

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DiscussionDiscussion

What problems did you come across in your experiment ?What problems did you come across in your experiment ?

How did you overcome these problems ?How did you overcome these problems ?

The scientific method is limited in a number of ways, e.g. by the extent of our basic knowledge and changes in the natural world. Can you think of any other factors that might affect the validity of your results.

In all practical work safety must be a major concern. Give examples of two safety precautions you observed when carrying out this investigation.

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Animals that move through waterAnimals that move through water

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Extended DiscussionExtended Discussion

1. 1. Some fish have fusiform (streamlined) bodies, e.g., Some fish have fusiform (streamlined) bodies, e.g.,

salmon while others are laterally compressed salmon while others are laterally compressed

(flattened from side to side), e.g., sole. The shape of (flattened from side to side), e.g., sole. The shape of

the fish’s body tells us a lot about its lifestyle. the fish’s body tells us a lot about its lifestyle.

Comment on this statement.Comment on this statement.

2. 2. In what way might the results be useful if you were In what way might the results be useful if you were

designing swimwear?designing swimwear?

© Sheila Porter – www.scifest.ie