Bag Blowup
Equipment: A weight, a sealed plastic bag with a tube attached and a plank of plywood that is roughly the same size as the bag.
What it does: When the bag is inflated, it lifts a weight placed on top of it.
Concepts Demonstrated: Small forces on small areas transfer to large forces on large areas.
Classroom assembly:
- Place the bag on the table.
- Place the piece of plywood on the bag to protect it from the weight.
- Place the weight on the plywood.
- Blow into the tube to inflate the bag. The weight will be lifted by the inflating bag.
Note:
- A textbook works very well as a weight.
Cautions: None.
Setup Time: Short.
Difficulty: Straightforward.
Visibility: High. This demonstration is appropriate for large lecture halls.
Related demonstrations:
References: PIRA 2B20.65
Original Construction: A tube was inserted into one corner of a sturdy square storage bag and the bag was sealed with tape. The bag is roughly the size of a first year physics text book.
Disclaimer: All demonstrations are posted for the convenience and benefit of faculty and staff in the Department of Physics at Simon Fraser University and are not intended for outside use. The author(s) assume no responsibility or liability for the use of information contained on this site. Warnings and precautionary measures listed on this site assume normal operation of equipment and are not inclusive. Demonstrations may pose a significant hazard and can, in some instances, result in death; reasonable safety precautions must be taken. Demonstrations should be performed by qualified individuals only.
Prepared by Jeff Rudd, 1999
Revised by Laura Schmidt, 2007