Surface Tension - Part 1: Retreating Pepper

Dr. Boyd introduces surface tension, explaining its effects and demonstrating how soap reduces it. The video includes two demonstrations: one with soap and one without, to show the impact on surface tension. The first demo uses water, dish soap, and pepper to illustrate how soap decreases surface tension, causing pepper to move away. The second demo tests the hypothesis that without soap, the pepper won't move, confirming the role of soap in altering surface tension. The video concludes with a teaser for the next part.

What is surface tension?

• The force that makes liquids evaporate quickly

• The tendency of fluid surfaces to shrink into the minimum surface area possible

• The property that allows liquids to mix easily with solids

• The ability of a liquid to expand its surface area

Which of the following is NOT an example of surface tension?

• A leaf floating on water

• An insect walking on water

• Water forming a dome on a coin

• Water boiling at high temperature

What happens when you add dish soap to water in the experiment?

• The pepper sinks to the bottom

• The water evaporates

• The water changes color

• The pepper moves away from the soap

Why does the pepper move away when soap is added?

• The soap increases the surface tension

• The soap decreases the surface tension

• The soap attracts the pepper

• The soap makes the water hotter

What was the hypothesis tested in the verification experiment?

• The pepper will dissolve in water

• The pepper will move without soap

• The water will change color without soap

• The pepper will not move without soap