For a physics/ engineering contest, I want to use a large balloon as an anchor point for a pulley. This would allow me to raise and drop masses.
However, in testing, when I pull on the pulley the balloon just lowers and when I stop pulling the string the balloon rises with the item in tow.
My theory for why this didnt work has to do with the momentum of the balloon vs the device being lifted
Is the balloon not large enough? Should i use multiple? Is this even possible?
Here is an illustration and a better description:
If I would like to use a balloon to hold up a pulley to allow items to be lifted into the sky.
In a real world test, when I pull the lifting rope (brown line). The balloon lowers. When I stop pulling, the balloon then lifts the payload back to the original position.
Some more observations that may help the discussion:
- There are guidelines that tether the balloon in place it would continue to rise if able.
- No matter how softly I pull the pulley line the balloon lowers.
- As noted in a comment below, I estimate the balloon is capable of lifting 4 to 6 lbs total and the payload is only 1/4 to 1/2 lbs
- The friction of the pulley is very small it is free spinning and the lines in this case are small strings
Also, while all I have is my gut reaction from seeing and feeling the forces; I would like to direct the attention back towards the momentum and/or inertia of the balloon. It seems "easier" to move the balloon. It does return to its equilibrium, but seems easier to affect with smaller forces. Perhaps due to its small mass?