How does the Venturi effect work in a Geyser Water Cannon toy?

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Discussion Overview

The discussion revolves around the operation of the Geyser Water Cannon toy, specifically how it utilizes the Venturi effect or related fluid dynamics principles to propel water. Participants explore the mechanics involved in the toy's design, including the relationship between pressure, fluid velocity, and the geometry of the cone.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes the Geyser Water Cannon as a cone that narrows from a wide diameter to a small opening, questioning how the Venturi effect contributes to the water being shot high.
  • Another participant argues that the phenomenon may not be the Venturi effect but rather a result of the principle of continuity, suggesting that fluid velocity increases and pressure decreases as it passes through a constriction.
  • There is a comparison made between the Geyser Water Cannon and a syringe, noting that both involve a smaller opening leading to higher pressure and velocity of the fluid.
  • Further queries are raised about the ability to increase pressure by modifying the cone's dimensions, with some participants expressing uncertainty about the physics involved.

Areas of Agreement / Disagreement

Participants express differing views on whether the Venturi effect is the correct explanation for the toy's operation, with some supporting the idea while others suggest alternative explanations based on fluid dynamics principles. The discussion remains unresolved regarding the precise mechanics at play.

Contextual Notes

Participants acknowledge a lack of formal physics education, which may influence their understanding of the concepts discussed. There are also references to specific pressures and dimensions without detailed calculations or consensus on their implications.

gloo68
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I have this toy I bought for my daughter. It is called a Geyser Water Cannon and supposedly it works using the Venturi effect. Basically it's a 2 foot cone that starts out with a wide diameter (1 foot) and narrows to about 1 inch - with openings on each end. When you pull down or push down this cone on a surface of water - it can shoot water up to 30 feet.

I am all confused by this talk of the Venturi effect as water travels from a wide volume to a narrow one.

Questions:
1. Is the water shooting higher not created because I am pushing and concentrating water up a narrow channel and thus the pressure created shoots the water higher??

2. Doesn't a syringe work in the same way with the opening being smaller in diameter than the barrel of a syringe? And thus the stream shoots higher because of pressure?
 
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I don't think it's the Venturi effect. That has to do with a reduction in static pressure when a fluid passes through a constriction.

From the wiki article on the venturi effect: According to the laws governing fluid dynamics, a fluid's velocity must increase as it passes through a constriction to satisfy the principle of continuity, while its pressure must decrease to satisfy the principle of conservation of mechanical energy.

It looks to me like it's simply a result of the principle of continuity. So I think the answer to both of your questions is, yes.

If this isn't right someone correct me.
 
Here is an advertisement for the "Geyser Water Canon" with a photo of the device, plus many comments from users. This may help others describe the principle of operation.

http://www.yoyo.com/p/geyser-guys-geyser-gusher-water-cannon-colors-may-vary-354192
 
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@ Drakkith - thanks so much for the reply.

So the next query is, Given a set force and size of the cone (volume wise), we can can actually increase the pressure to almost any reasonable pressure (i.e. 500 Kpa?) by just making the tappering part more narrow and/or make the opening smaller correct?
 
gloo68 said:
@ Drakkith - thanks so much for the reply.

So the next query is, Given a set force and size of the cone (volume wise), we can can actually increase the pressure to almost any reasonable pressure (i.e. 500 Kpa?) by just making the tappering part more narrow and/or make the opening smaller correct?

I want to say yes, as that would make sense to me, but I have no formal physics education so I can't be sure.
 
Drakkith said:
I want to say yes, as that would make sense to me, but I have no formal physics education so I can't be sure.

@ Drakkith - ok thanks for your efforts.

If anyone else has thoughts on this I would appreciate. Thank you in advance.
 

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