### plaything:

Balloon
* Most balloons are made of rubber
  - stretchy rubber
* Most balloons contain gases
  - noble gases
* Most balloons fill with air
  - hot air
  - hydrogen oxygen
* Most balloons use for balloon flight
* Some balloons are used by underwater archaeologists.
* Some balloons carry instruments
  - contain hydrogen
* Some balloons fill with fluid
  - pure hydrogen
* Some balloons have heat sources
  - mass
  - use hydrogen
  - weigh kilograms. * are very big. Big balloons are used for people to fly into the sky. Big balloons are called aircraft. Most balloon aircraft are filled with hot air. They are called hot air balloons
* allow payloads tobe lifted without the vibrations and G-forces associated with rockets.
* are a great example of how the pressure and the volume of a gas are interconnected
  - major choking hazard for young children
  - popular toy for small children
  - an inexpensive way to add color
  - easy to conceal and carry
  - envelopes
  - especially dangerous for young children
  - kind of like insects
* are located in air
  - birthday parties
  - circus
  - fairgrounds
  - grocery stores
  - skies
  - red
  - second only to food as the most frequent cause of choking deaths
  - the most common cause of toy-related choking death among children
* are used for birthday parties
  - celebration
  - decoration
  - flies
  - many purposes
  - poppings
* can choke and kill a child.
* come in all shapes, sizes and colours.
* do float in the air and in water.
* drift entirely with the wind, with the pilot using the burners just to climb or descend.
* fly best in cool weather with wind speeds less than seven knots
  - twice a day, in the morning and in the evening
* generally launch at sunrise, or in the last couple hours before sunset.
* help scientists measure temperature, humidity, and acquire atmosphere samples.
* is an aircraft
* lift better in cold air than in warm air.
* may have charge
  - negative charge
* mould masks Blow up a balloon and hang it from a string.
* normally launch early and late in the day.
* often seem to defy gravity.
* operate through the basic principles of gravity and heat transfer.
* pops at weakest spot on surface.
* pose a choking hazard to young children
  - threat to marine life and sea birds when they are mistaken for food and eaten
* provide a common device with which most children have experience.
* tend to fly better in the morning, when the surrounding air is cool
  - rise when gravity pulls downward
  - first flight
* use for first man balloon flight
* vector graphics engine that brings a new quality of graphics to Squeak.

### plaything | balloon:

Big balloon
* are called aircraft
  - made from fabric
+ Balloon: Aircraft :: Toys
  * A long time ago, balloons were made out of animal bladders. Now small balloons are made from a thin and stretchy material like rubber or plastic. Big balloons are made from fabric.
  * Some balloons are very big. Big balloons are used for people to fly into the sky. Big balloons are called aircraft. Most balloon aircraft are filled with hot air. They are called hot air balloons.

### plaything | balloon:

Gas balloon
* Some gas balloons carry people.
* are use for sport ballooning, scientific research, and many other purposes.
* fly as a result of a lifting gas in their envelopes.
* get their initial lift from the helium or hydrogen pumped into their envelopes.
* have gas of low density in their envelopes.
+ Balloon (aircraft), Kinds of balloon aircraft: Aerospace engineering
  * Gas balloons are not hot. Gas balloons have gas of low density in their envelopes. Examples of the gas used in gas balloons are helium and hydrogen.