To calculate the buoyancy of a balloon, you will need to know the volume of the balloon, the density of the air and the density of the gas inside the balloon. The formula for calculating buoyancy is: Buoyancy = (Density of Air - Density of Gas) * Volume of Balloon.
The density of air varies depending on altitude and temperature, but on average it is 1.225 kg/m3 at sea level and 20 degrees Celsius.
The density of the gas inside the balloon will depend on what type of gas is being used. For example, if helium is being used, the density would be 0.1785 kg/m3. If you are unsure of the gas being used, you can estimate an average density of 0.2 kg/m3.
The appropriate balloon size for a 6 year old boy would depend on his weight and the weight of the balloon. As a general guideline, the balloon should have a lifting force of at least 1.5 times the weight of the child. You can use the formula in question 1 to calculate the appropriate volume of the balloon.
Yes, it is important to always supervise children when playing with balloons to prevent any choking hazards. Also, make sure to use high quality, sturdy balloons to avoid any potential popping or bursting. And as always, follow the instructions and warnings provided by the manufacturer.