PROCEDURE: 1.   Nail the wood square to the 12” dowel rod 2.   Glue   two   wooden   rulers   together   at   their   centers.   The   rulers should be glued at a 90º angle to one another.  Make sure the holes line up with room to place a nail through them.   3.   Place a washer between the dowel rod and the rulers and attach the cross to the dowel rod using the remaining nail.  The nail should go through the hole in the rulers. 4.   Use two thumb tacks per cup and attach a paper cup to each end of both rulers.   5.   Use a red marker or red paint and put a large X on one of the cups. 6.   Take your anemometer outside and measure the wind speed.  To do so, count the number of times the cup with the red mark passes in front     of    you     in    30    seconds.       Multiply     by     two     to     get revolutions/rotations per minute (rpm).         OBSERVATIONS:   1.   What was the wind speed? 2.   If the number of turns made in 30 seconds was 15, what would the wind speed be? 3.   What would the wind speed be if the anemometer made 40 turns in 30 seconds? CONCLUSIONS: 1.   How does the structure of an anemometer allow you to measure wind speed? 2.   How might your anemometer be less accurate than the ones that weather forecasters (meteorologists) use? 3.   Are there any structural design flaws that might have decreased the accuracy of the anemometer you built? 4.   How big does an anemometer have to be to measure wind speed? If you made a bigger anemometer, would the wind speed you measured change?  If you made a smaller anemometer, would the wind speed you measured change?