## Step 14: The Physics Behind It

The physics behind the bottle rocket is Newtons 3rd Law that "For every action there is an equal reaction."  The water and air pressure cause the water to push out of the rockets engine and move upward. When the rocket is coming down, the parachute gets released from the rocket.
<p>Does the d stand for diameter to find the circumference???</p>
thnx i was looking for this everywhere
moi two
<p>If your going to speak froench, do it ricght. It's &quot;moi <em>aussi</em>&quot;</p>
If &quot;your&quot; going to speak English then spell &quot;you're&quot; right. Haha. Kettle, this pot is calling you black.
<p>uhh kinda not helping</p>
<p>if the link doesn't work anymore, what do we use?</p>
<p>noob</p>
<p>i agree</p>
<p>really cool!! i give it a big thumbs up</p>
<p>Thank you</p>
<p>This looks awesome, but I do have a question. Do you just use the standard ,fill the bottom with water and hook it up to an air supply? Just wondering. but otherwise awesome project. :)</p>
<p>u said u need not a engine.</p>
<p>awesome stuff bros</p>
looks awesome but just 2 much parts<br>
<br /> We have a sudden rash of water-rockets. I'm guessing it's a school project?<br /> <br /> Have you all seen the relevant groups:<br /> <br /> https://www.instructables.com/group/H2Orocketables/<br /> <br /> https://www.instructables.com/group/rockets/<br /> <br /> <br /> <br />