Water Rocket-density,temp,drag

[thereddevil]

I have a question about rockets
This involves the d and temp of the water

The density is linearly proportional to the mass and therefore linearly proportional to the momentum of the expelled liquid, gases, whatever... Simply plug in $\rho•V$ instead of m.

m | -
a | -
s | -
s | -
| -
|-_________________
density
So graph should look like ^^
and pV =(proportional to) d
d=m/volume
d=m(mass)
d=mv
density proportional to velocity

Are sure that the greater the density of the water (using salt) the greater the momentum( initial velocity of the rocket) ?
Because thinking practically if you were to put lots of salt in, then it would not work normally. However i do understand where your coming from because the more fuel that is expelled at x speed the greater the velocity so therefore the greater the mass of this fuel at the same x speed the greater the v, right?

Also for temp
pV=nRT ot pV/nR = T
d=m/v
to form V=m/d

therefore
T= (pm/d)/nR
if density is proportional to mv
T is proportional to pm/velocity ?
or T proportional to 1/v
making graph curved like
y axis velocity
|
|
* |
** |
*** -
********* -
***************** - - x-axis temperature

Is this right because I am really stuck as i didnt have time to finish all experiments.

Also working out the drag of the rocket.
Would i need to work out the Cross Sec Area or the frontal surface eg the whole nose cone plus the wings where you can see them looking down onto it??

thanks for the help!

 

[LightHero]

Yes, the greater the density of the water (using salt) the greater the momentum and initial velocity of the rocket. The temperature is also proportional to the velocity, as you've figured out, with a graph that looks like what you have described. For drag, you need to calculate the cross-sectional area of the rocket. This would be the total surface area of the rocket, including the nose cone and wings, that are visible when looking directly down at its center.

 

[charng]

Hello, thank you for your question. I can provide some insights on water rockets and how density, temperature, and drag can affect their performance.

Firstly, the density of the water in the rocket will definitely have an impact on the initial velocity of the rocket. This is because as you mentioned, the more mass that is expelled at a given speed, the greater the momentum and thus the initial velocity will be higher. However, there is a limit to how much salt can be added before it starts affecting the overall functioning of the rocket. Too much salt can increase the density to a point where the rocket may not be able to lift off or may not reach a significant height. So it's important to find the right balance of salt to water ratio for optimal performance.

Regarding temperature, it can also have an effect on the rocket's performance. As you mentioned, T= (pm/d)/nR, so temperature is proportional to the pressure, mass, and density. This means that if the temperature of the water is increased, the pressure inside the rocket will also increase, leading to a higher initial velocity. However, this also means that if the temperature is too high, it can cause the water to expand and potentially rupture the rocket. So it's important to monitor the temperature and not let it get too high.

As for drag, it is important to consider both the cross-sectional area and the frontal surface of the rocket. The cross-sectional area is the area of the rocket when viewed from the side, while the frontal surface is the area when viewed from the front. Both of these factors can affect the drag on the rocket, which in turn affects its speed and trajectory. It's important to minimize drag by making the rocket as aerodynamic as possible.

I hope this helps answer your questions and provides some guidance for your experiments. Remember to always take safety precautions and follow proper procedures when conducting experiments. Good luck!