Oldie but a goody from the Solution Sleuth 1989, The Learning Works, Inc., a little hands on physics lessons with balloons.
Compare, predict, and evaluate the performance of two different Jet Balloon designs.
What you need: 2 pieces of fishing line or other low friction string, masking tape, drinking straws, 2 balloons, and a way to fasten the line to a wall or other stable surface.
Jet Balloon #1 (shown left) uses 2 pieces of straw sections while Jet Balloon #2 (shown right) uses one single section of straw.
Inflate the balloons equally but do not tie the ends. Secure the straw section(s) to the balloon. Line up with the balloons on the open end of the line, give a countdown, let the nozzles go, and watch them fly! Now discuss all the forces in play.
That photo of Balloon Jet #1 gives a good hint as to which jet was going to win this race! Those misaligned sections of straws added even more forces (friction force) than planned on. We 'corrected' the design and it increased the distance and speed but it wasn't enough to beat Jet Balloon #2 in any of the races we ran.
How about measure distance and speed of different inflation ratios of the balloons. How much more would you have to inflate Jet #2's balloon to beat Jet #1?
Helpful Discussion Points:
- Newton’s First Law: Objects at rest will stay at rest and objects in motion will move in a straight line at constant speed unless acted upon by a force.
- Newton’s Third Law: For every action there is always an opposite and equal reaction.
- A surface supplies a friction force parallel to the plane which always opposes the motions.