The Life and Science of Percy Julian
Activities and Readings
7A.2 (Thought Experiment)

Separating Coins

Have you ever taken coins to a bank to have them sorted and counted? Maybe you have taken a bag of coins to a machine in the supermarket to have them counted and converted to bills. If you have a coin sorter at home, you may have wondered how the machine separates the pennies, nickels, dimes, and quarters.

Assume you have a pile of coins like that pictured in photo 1.

photo of coins mixed up

Based on what you see here, how do you think a coin sorter separates the coins so that you end up with what you see in photo 2?

photo of coins sorted

The mixture contains pennies, nickels, dimes, and quarters as seen in photo 3. How are they the similar? How are they different? How does this help you figure out how a coin sorter works?

photo of individual coins

Do the methods you proposed for separating the marble mixture and for how a coin sorter separates coins have anything in common? What’s the commonality or commonalities?

Next: Separating Plastic and Metal Beads

Return to the Main Story

Return to the Main Story
Meanwhile, In the Rest of the World...