Energy pumped into a water rocket? (soda bottle rocket)

In summary, the conversation discusses calculating the energy in a water rocket by measuring the work done by compressing air inside a 2L soda bottle. The suggested methods include using the force and stroke of a pump, and using the pressure and temperature relationship. However, there is uncertainty about how to calculate the energy due to losses and heating in the system. Suggestions for measuring or calculating the temperature and number of molecules in the bottle are also mentioned.
  • #1
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Homework Statement


So you're shooting off a water rocket, which has some water inside a 2L soda pop bottle. You're then pumping (for example, a bicycle pump) to compress more and more air inside to a higher pressure.


Homework Equations


Well, work = F*d. If you measure the stroke of the pump, and the force (ha ha, we pictured putting a bathroom scale on top of the pump handle), you could calculate that work. But you miss losses and heating through the system.

I'd prefer to think about the pressure in the bottle. From Boyle or Charles or one of those fellows, we can say P1/T1=P2/T2. If you have ambient temp and pressure, you could somehow measure or calculate the "under pressure" temperature.*

Temperature relates to energy (kinetic), and you can calculate the volume of the bottle.

So how can we calculate the new "under pressure" energy in the system??


The Attempt at a Solution


Ha, not much so far, that's why we need help. Can we calculate the moles and thus the number of molecules in the volume of the bottle, then multiply by delta temperature?

?



*ideas as to HOW welcome. So far we just pictured painting one side of the bottle black and using an infrared thermometer to read the temp.
 
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  • #2
bump-no takers? Too much like Chemistry? Even WAG welcome...
 

1. How does the amount of water affect the height of a water rocket?

The amount of water in a water rocket affects its height because it determines the mass of the rocket. The more mass the rocket has, the more force it will need to overcome gravity and reach a greater height. However, too much water can cause the rocket to become too heavy and not reach a high enough altitude.

2. What is the ideal air pressure for launching a water rocket?

The ideal air pressure for launching a water rocket depends on the size and shape of the rocket, as well as the amount of water inside. Generally, a pressure of about 50-60 psi is recommended for a 2-liter soda bottle rocket.

3. Can other liquids besides water be used in a water rocket?

Yes, other liquids such as vinegar or lemon juice can be used in a water rocket. However, these liquids may not provide the same amount of thrust as water and could potentially damage the rocket if not used correctly.

4. How does the angle of launch affect the flight of a water rocket?

The angle of launch, also known as the launch angle, affects the trajectory of a water rocket. A launch angle of 45 degrees is typically recommended for maximum distance, but a lower angle can result in a higher flight path while a higher angle can result in a shorter flight path.

5. What is the maximum height a water rocket can reach?

The maximum height a water rocket can reach depends on various factors such as the design of the rocket, the amount of water and air pressure used, and external factors like wind. On average, a well-designed water rocket can reach heights of 100-200 feet.

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