Playing Cards and Pennies

Objectives

• Describe a scenario that demonstrates the property of inertia.

Materials

• Per student or small group:
  a cup
  a penny
  playing or index card (stiff paper)

Key Questions

• Before the demonstration is performed, what forces are acting on the cup?
• Before the demonstration is performed, what forces are acting on the card?
• When you flick the card, what forces are acting on the penny?
• Does this trick work with a lighter object (like a cotton ball)? Why or why not? Experiment and see how light an object can be for the trick to work.

What To Do

1. Have students set up a playing card over the mouth of a cup, and place a penny on top, directly over the centre of the cup.
2. Challenge them to figure out how to get the penny in the cup without touching the penny or lifting the card.
3. Once they have found the solution, have them try with a stack of pennies. How many pennies can they drop into the cup at once?

• Solution: Students should flick the card swiftly with their finger, to send it out from under the penny, allowing it to drop into the cup.