Jet Propulsion

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Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• Fix a balloon to a styrene foam board. Attach a straw to the balloon so the discharging direction is stable.
• Inflate the balloon and let it go. Air discharges from the straw, and the board moves in the direction opposite to that of the escaping air.
• This principle is called “jet propulsion” and is used in jet airplanes and rockets. In such vehicles, burnt gas is discharged from the back at high speed, thereby providing a propulsive force.

[Keywords]	jet propulsion, momentum theory, action-reaction, jet airplane, rocket
[Reference]	“The Wonders of Flow” Japan Society of Mechanical Engineering, Kodansha Blue Backs pp. 114-117