Balloon Wars

Step 1:  Calculate area density

            a) find mass of paper     _________g

            b) find area of paper      _________cm²

            c) divide mass by area   _________g/cm²

 Step 2:  Calculate net upward force

            a) place mass on scales, record:             ___________g

            b) attach balloons, record new mass __________g

            c) subtract two reading (NUF): _________g

 Step 3: Calculate area of material needed

a) if NUF should equal 15 grams (this means that if the balloon is attached to an object of 15 grams it should be able to lift it off the ground but not rise)

b) pick a safety margin (example: 2 %)  if balloon can lift 15 grams we take 2 % of 15 grams 
(0.3 grams) and subtract from 15 g to get target lift mass of 14.7 grams

c) to find area of material needed (cm²) we must the the density formula: (hint:  we just found mass needed and we calculated the area density earlier):   
                area needed =  target lift mass
                                              area density

d) find dimensions (must be perfectly square) of paper needed:  (hint area = side²   -  square root of area needed gives length of each side)

            e) teacher can check for square by checking diagonals - they should be equal)

 Step 4:  Test Flight

            a)  attach balloon to target paper at floor level and use stop watch to time ascent to ceiling

            b) find area to test that has no strong drafts.