Science Buddies: "Ask an Expert"

Our boat doesn't move. We have followed the directions and everything is right but the boat wont move. We are only using hot water in the tube. That is what the directions state. HELP

Hello and welcome to the forums.

I'm not sure which experiment you are performing, is this the one? http://www.energyquest.ca.gov/projects/steamboat.html. We have an easier time answering questions if you can post as much information as possible about your experiment. When you say "We are only using hot water in the tube", I have to assume that you are lighting the candles? The hot water will not turn into steam without the heat input from the candles. Is there a good clean hole through the stopper / cork? Please give us more information and we'll try to help.

Keith

Yes I am lighting the candle. The project is from Science buddies I ment that I didn't use anything else in the tube like baking powder of anything else. The water is boiling and steam is coming out but the boat doesnt move. Why?

Hi Malissa1234,

I'm going to assume that you're following the procedure described in the link that Keith posted. If there's a similar Science Buddies project, I haven't been able to find it by searching the site. Could you post a link to the directions you're following? That would be especially helpful if the procedure is different.

The idea is that as the contents of the tube heat up, the air/water vapor will expand and escape through the hole in the cork. Because of conservation of momentum, the boat must move in the opposite direction. Here are a few troubleshooting ideas:

-- Is there steam coming out of the hole in the cork? If you aren't sure, you could place a mirror near the hole to see if it fogs up (to avoid burning your hands). If there's no steam coming out of the hole, you could try moving the tube closer to the candles in case its contents aren't being heated enough. You could also check the cork/tube seal or any other places steam might be leaking out.

-- Does your boat have a pointed bow at one end, and is the cork at the opposite end? The pointed bow reduces the drag force opposing motion in that direction. If your cork is at the wrong end, it would require a greater force to move the boat.

-- You say the boat isn't moving, but is it rotating at all? That would be a sign that steam is being produced, but either it's not being channeled properly through the hole in the cork, or the boat isn't balanced properly (weight distribution or shape).

Let us know if that helps!

Amanda