Up: Glassmaking
Gilbert: 12 of 65
|
|
| |
The "why" of it
You boys who have the Gilbert set on
"Hydraulic and Pneumatic Engineering" will know the "why" of
the last three experiments. Any body floats in water if it is
lighter than an equal volume of water. Water is practically
FIG. 16
DRAWING A THIN TUBE
|
incompressible but air is very compressible: thus when you press
down on the stopper, you force water into the balloon and compress
the air in it; when you release the stopper, the compressed air
in the balloon expands and drives the water out. When the weight
of the balloon and the weight of the water in it are together greater
than the weight of water displaced by the balloon, the balloon sinks;
when they are less, it rises.
Experiment 10. Fun with thin tubes.
Hold a piece of No. 2 tubing in the lamp
flame and turn it constantly. When it is red hot and soft, take
it out of the flame and pull your hands apart until the tube is
stretched ten or twelve inches (Fig. 16). is the tube in the shape
shown in Fig. 17?
FIG. 17
A GLASS TUBE STRETCHED
|
Allow the tube to cool, break the large
ends away from the thin tube, place one end of the thin tube in a
glass of water, and
|
|
