Balloon Rockets, part 2

As promised, Balloon Rockets, had a part 2.  Not only is it fun to watch balloons fly all over the room, it's fun to direct their path with strings.  What are we learning with this demo?  For every action, there is an equal and opposite reaction (Newton's Third Law).  The air escapes out of the balloon, propelling it forward.

Materials:

• Balloon(s) (balloon pump optional)
• String (we used embroidery floss and plain old cheap yarn)
• Straw piece
• Scotch tape

Set-up:

• Tie string to something immovable (we used a toy ride-in car and a plastic mug filled with laundry quarters, not shown).
• Put straw piece on string.
• Hold other end, making the string as tight as possible - slack in the string doesn't give good results.
• Blow up balloon, twist and pinch the end. 
• Attach balloon to straw with two pieces of Scotch tape.
• Count down and let go.
• Observe what happens!

Variations:

• Slack the rope (giving the other end of the string to the kid to hold will most likely do this).
• Try different sized balloons, note the differences.
• Try different shaped balloons, note the differences.
• Try different sized straw pieces.  Which size works the best?

Warnings:

• String the string across the room, above or out of the main walkway - or take down when not in use.  The string is very tempting for a young child and can cause injuries if not careful.

**Please excuse the apartment mess.  Our science workshop is in full gear.