USING WIND TO DO WORK
Adapted from NEED Project activity
Problem: What is the maximum load that can be done by wind?
Materials: empty plastic bottle with cap, water, windmill blade template, one large straw, one smaller straw, tape, 50 cm of thread, paperclips, bull clip, 3 straight pins, fan, ruler, hole punch, maker, stopwatch.
Procedure:
1. Fill am empty plastic bottle ½ full with water, place cap on the top. You might need more water in the bottle if you wish to test it outside. The water acts as ballast.
2. Cut the large straw so that you have an 8-9cm length, discard the remaining portion.
3. Tape the large straw horizontally to the top of the bottle cap so that there are equal amounts of the star on either side of the tape (balanced on top of bottle). Set aside.
4. Prepare the windmill blades using the windmill blade template (see attached).
5. Measure 0.5cm from the end of the small soda
straw and make a mark. Insert a pin through the
small soda straw at this mark. This is the front of
your blade assembly.
6. Slide the straw through the front of the windmill
blade template (cut out) until the pin rests the end
of the larger straw. Slide the center of the blade
template (cut out) onto the smaller soda straw then
turn the ends of each blade and slide onto the smaller
soda straw through the punched out holes. Remember
to keep the blades turned in the same direction. Insert
a straight pin through the smaller soda straw in the front
of the blade assembly to secure it.
7. Place a pin through the smaller soda straw at the back
to hold everything in place.
8. Tape a piece of thread to the end of the smaller straw.
Tie the other end of the thread to a paperclip. Turn the
smaller soda straw by hand to wind the thread onto it.
8. On the very end of the smaller soda straw fasten a
bull clip in place for balance and to keep the thread
wound around the straw.
Investigation:
a. Write a hypothesis regarding wind doing the work of raising your paperclips.
b. Allow the thread with attached paper clip to unwind. Place your
Completed unit in front of a box fan. Turn on the fan.
c. Time how long it took to have the single paper clip drawn upward to the straw.
Was your hypothesis correct? Write your conclusion
d. Add paperclips, write a new hypothesis and try again. How long did it take? What conclusion can you draw from this activity?
e. In your investigation what were the independent and dependent variables?
Extension:
a. Take your unit outside and see how many paper clips you can lift using the wind.
b. What variables can you change in this investigation?
c. Create a new investigation changing one variable at a time.