Hot Air Balloon

Essential Question
What powers a hot air balloon and how?

Objectives

 * Construct a functional hot air balloon.

Introduction & Student Background
In this activity, students will build a hot air balloon using everyday items. Hot air rises while cold air sinks, so when air is heated via a candle or a hot air dryer, it rises, but is trapped by the balloon, so it also causes the balloon to rise.

Materials

 * Dry cleaning bag
 * Birthday candles or hot air dryer
 * Razor blades
 * Plastic drinking straws
 * Tape

PREP

 * 1) Cover the table in newspaper or butcher paper.
 * 2) Place two straws end to end, making a longer straw. Tape together. Do the same with a second pair.
 * 3) Cross the straws, making an X. Tape them together at the X junction.
 * 4) Cut slits along the end of the straws long enough to hold the base of a birthday candle. Do not cut near the intersection of the straws.
 * 5) Burn the candles until they are reduced in length by one half. This is to reduce the mass you are lifting. Place the candles in the slits.
 * 6) Open the dry cleaning bag. Separate the pleats in the bag so that when it inflates, it inflates fully.(If the plastic film adheres to itself, the same mass will confine a smaller volume of hot air, reducing the resultant lift. )
 * 7) Seal the hole where the hanger would go into the bag.
 * 8) Use pieces of tape to seal any other holes found.

ACTIVITY
Variation: A hot air dryer can also be used in lieu of a candle.
 * 1) Attach the bag to the ends of the crosspiece. Divide the bag evenly between the ends of the crosspiece. If you put too much bag between any two crosspiece ends, it will gap when inflated and allow hot air to escape.
 * 2) Hold the plastic film away from the candles and light the candles.
 * 3) Let the bag fill and steady it until it gets sufficiently warm to start rising.

How it Fits to Standard

 * Use simple tools and materials to solve problems in creative ways.
 * Answer questions by explaining observations of the natural world.

Follow Up
TBW