(This exercise may be printed as a PDF.)
Design a boat that will float and hold many pennies;evaluate the design.
Science Concept: Buoyancy
A fluid exerts an upward force on objects less dense than itself. An object floats if water's density is greater than the object. By enclosing air, which is much lighter than water, even steel boats can float. Without buoyancy, river and sea transportation, exploration and commerce would not have been possible.
- Sheets of aluminum foil, approximately 12" x 6" (keep the size uniform)
- Tubs of water pennies, up to 100 per tub bowls for pennies
- 1 tsp bleach per tub paper
- 2 buckets for used foil
Fill tubs with 3"- 4" of water and add 1 tsp of bleach to each tub. Cut foil into uniform sizes sheets. Put pennies in bowls. Provide towels to mop up spills.
Directions for Students
- Shape a piece of aluminum foil into a boat shape.
- Float the foil on water.
- Add pennies until the boat sinks.
- Count the number of pennies the boat held.
- With a new sheet of foil, redesign the boat hull and repeat test.
- Record the number of pennies held and student's name on the board.
Questions for Students
- What can you say about your hull design?
- What is the equivalent "boat" to your design? Canoe, barge?
- How does the placement of pennies affect the number the boat holds?
- What kinds of boats are used on the Mississippi River to haul cargo? Why?
- What advantages do barges have over deep hull boats?
Note to teacher:
Give students the opportunity to be as creative as possible with the hull shape. Make no suggestions, unless to show how to fold up one side to make an edge. The best designs are flat barges with small sides. The placement of pennies also makes a difference in the number held. The record for one sheet of 8" x 12" foil is around 280 pennies. Recycle the foil along with your pop cans.
Copyright 2001 Science Museum of Minnesota. Used with permission.