Hover Balloon

I did this activity during my first outreach with the Society of Women Engineers as a sophomore or junior in college. They were hosting an science/engineering event for the Girl Scouts. I was placed at a table where we tried to make helium balloons neutrally buoyant. In other words, we wanted the balloon to not sink or float; we wanted them to hover.

I really didn't remember the specifics, just a helium balloon, a small cup, and items to weigh it down.

Remembering that the activity was fairly simple, I recreated it with J and John this afternoon. J was thrilled to have a floating balloon around.

Goal:
Get the balloon to hover in the middle of the room without rising to the ceiling or falling to the ground. 10 seconds in about the same spot would be ideal.

Materials:
1 helium balloon with string (this is a great activity for after a party!)
1 small Dixie-like cup
Hole punch
Various size paper clips or other small, light objects (ie. string, rubberbands)

How to do it:
1. Fill balloon with helium, tie off the balloon, and tie the string to the balloon (if you don't have a balloon already ready).
2. Punch 2 holes across from each other on the cup.
3. Tie the balloon string to the cup - we threaded ours through the two holes and then to the string (think triangle).

4. Ask your kid if he/she thinks the balloon will float or sink when you let go of the balloon. Point out that there is a cup on the end of it. Repeat this question after you add each piece of weight.

Ours floated to the ceiling

5. Add large paperclips one by one. Ask whether you think the balloon will sink or float with this paperclip.

6. When you add enough weight that the balloon sinks to the ground, you've added too much weight. Remove the last item you added and add something smaller.

Too many paperclips!

7. When you get close, use something like string or yarn that you can cut little pieces off of to remove weight little-by-little as needed.

Ours floated with:**
2 large paper clips
3 small paper clips
Piece of balloon string/ribbon that we kept cutting until we got it perfectly hovering in the middle of the room

**Note that not every balloon is the same. It'll depend on the amount helium in the balloon, size of the balloon, weight/length of the balloon string, size/weight of Dixie-like cup, and the weight of everything that you place in the cup to get it to hover.

Videos: (since pictures are a moment in time)

Too little weight:

Too much weight:

Just right:

This activity might just be our next Saturday Science in the Park Day lesson.