Science Buddies: "Ask an Expert"

Instead of just telling you what these variables are, I'm going to try to help you figure it out on your own.

First, let's think about what variables you have. The cans are definitely the same in every experiment. But what about the length of the string between the ruler and can? What about the atmospheric pressure in the room? Then, we have the distance between the cans, the time it takes for the cans to collide, and the 'wind speed' of the hair dryer.

So, which of these are you changing? You already said that those should be your independent variables. What are you actually measuring? This is your dependent variable. I suspect you might be confused because the way this experiment is written up, you have two independent variables and one dependent variable. Does that help?

You might also think of some additional control variables, beyond the ones that I mentioned.

All of those are correct--with the exception that you possibly have a typo--the distance and the wind speed are the independent variables--they are two separate variables, not just one single variable. Apologies if you already knew this and just meant to write 'variables'!

Let us know if you need any additional help.