Figure
out what affects how well the balloons stay afloat and move.
What you'll
need
Rubber cement
plastic dry-cleaning
bag/garbage bag (any large thin plastic bag will work)
paper clips
hair dryer
2 large books
or other heavy objects
camera
stopwatch
Getting
started
Close up any
of the tiny holes in your plastic bag (especially the dry-cleaning bag) with
the rubber cement, so that the only opening is the large one where the clothes
or garbage goes in.
Attach several
paper clips around the large opening.
Plug in the
dryer (don't turn it on yet), and set it up between the two books so the nozzle
points up. Be careful not to block the side intake fan.
Set the dryer
to the hottest setting, and turn it on.
Open the bag
and hold it with the opening over the dryer so it fills with air like a balloon
(watch out that you don't burn yourself on the hot air from the dryer).
When the bag
is completely full of air, let go.
What happens?
Take pictures!
Time how long
it takes for the bag to rise, and how long it stays afloat.
What next
Creation
and invention:
Try other sizes
and types of plastic bags. What works best - what rises fastest and floats
longest? Do some float higher than others?
Make a graph
of the rising and floating times for different bags.
What happens
if you try this in a colder or warmer room?
Try other heat
settings on the hairdryer - do the bags rise as fast or high or float as long?
Graph your results.
Try adding more
or fewer paper clips to the bag - how does this change the flight? Graph your
results.
Discussion:
What causes
the bag to rise and fall?
How does a real
hot-air balloon work (it's not by hairdryer!)?
Why don't we
use hot air balloons to travel?
How are helium
balloons different from hot air (nitrogen and oxygen) balloons?
Besides air,
where else do things float? Is it for the same reason?
Field
trip possibilities:
Take a
ride in a hot air balloon, or visit a festival
