Module 3 (pt 2)

Question 1

6. (Read story on page 80) What could be done to reduce or eliminate the unwanted experimental variables?

Answer 1

The experimental variable of the washers can be reduced by making sure all washers are the same brand and model, and by making sure they are all relatively new. You can reduce the differences in water temperature by monitoring the temp. of the water as it enters each washer and making adjustments to keep the temp. the same. The experimental variable of the shirts can be reduced by making sure they are all from the same manufacturer, the same style, and the same fabric. Finally, the experimental variable of the amount of stain.

Question 2

7. (Read story on page 80) Are the data collected objective or subjective?

Answer 2

subjective

Question 3

8. Why can a carefully placed needle float on water, even though a needle is denser than water?

Answer 3

surface tension

Question 4

9. What does soap do to the surface tension of water?

Answer 4

reduces the surface tension

Question 5

10. (Read question 10 on page 80)

Answer 5

the liquid must have a larger surface tension than water

Question 6

11. (Read question 11 on page 80)

Answer 6

You should give half the volunteers the fat-free potato chips and the other half should get potato chips that have been on the market for years and seem to have no problems associated with them. The volunteers then can keep a log (or you could observe them) for the next few hours to see if any stomach cramps occur. This should definitely be a double-blind experiment.

Question 7

12. (Read question 12 on page 80)

Answer 7

This should be a single-blind experiment