Science Buddies: "Ask an Expert"

For this project I have decided to use 3 substances. A recurring issue I face is that the raft either does not move, or it veers to the right. This has been most apparent with the vinegar. It remains on top of the sponge and for some reason unknown to me, prevents the raft from moving. On a separate issue, I cannot leave the raft in the water without having it move on its own. If anyone knows how to fix either of these issues, your help would be greatly appreciated.

Sponge size: 1.5cm by 1.5cm
Raft size: 6cm by 12cm
Raft hole size: 2cm by 2cm

Hi whydoialwaysneedhelp,

I'm assuming that you're working on the project described here:

https://www.sciencebuddies.org/science- ... ce-tension

If your raft doesn't move, it could be an indication that the liquid your added to the sponge had no effect on the water's surface tension. Does your raft move when you put a couple of drops of liquid detergent on it? If so your raft works.

If your raft veers to the right (or left), your raft may not be symmetrical. You might check to see if the cut out for the sponge is centered at the end of the raft and that the raft is “square” at all four corners.

If your raft moves as soon as you put it in the water there may be some residual detergent on the sponge. You might try cleaning the sponge or using a new piece of sponge.

I hope this helps. Please ask again if you have more questions.

A. Norman