Brian carefully filled a glass with water and then gently added paper clips to c
ID: 976008 • Letter: B
Question
Brian carefully filled a glass with water and then gently added paper clips to count how many he could add before the surface tension of the water broke. He had added 20 paper clips without breaking the surface when his little brother Alec accidentally knocked over the glass. Alec tried to help clean up the mess but, he had been eating pizza, and his hands were greasy. Brian quickly washed the glass with dish soap and started again. The second time, Brian only added 15 paper clips, and the surface tension broke.
Explain why Brian needed more than 20 paper clips to break the surface tension the first time and only 15 paper clips the second time. What is different about the surface tension of the water in the glass?
Explanation / Answer
ANSWER
Soap decreases the surface tension of water. The glass was washed with soap and then used in second attempt. The soap particles remaining in glass had decresed the surface tention of water hence it could hold only 15 pieces.