Question about variables on a science fair project.?

Question

My son is in the 5th grade and is doing a science fair project. He is testing the buoyancy of a aluminum foil ball filled with ten pennies, compared to a aluminum foil boat filled with ten pennies.
Now this may be cheating, but I have no idea what to do, so I can't help him much so I need some help.
What are variables? And how are they used here?
Thanks.

Answer 1

Variables are the parameters you control, and the effects you measure. There are two kinds -- independent variables and dependent variables. For example, the shape of the aluminum foil is an independent variable. You control it. The buoyancy of the pennies in the foil is a dependent variabe. It depends on the independent variable. If your experiment was to measure the effect of sunlight on plant growth, the independent variable would be "time in the sun," and the dependent variable might be "growth of the plant."

You might measure buoyancy by simply determining if the objects sink or float. Alternatively, you could measure the amount of water displaced by the objects like this: Fill a measuring cup (ideally with many markings for precise measurement) with water. Put in the foil-pennies, and see how much the water level rises. This is a measure of how deep the objects sank.

Answer 2

A variable is any number in an equation that can be changed. For example 2x=? the x is a variable if I say 2x=10, x if 5.

If you need a better understanding of the physics and Archimedes Principle, basically, the boat should have more of a bouyancy force than the ball. The ball (I'm assuming, unless you have magic foil) sinks, when it does this, it displaces its volume in water. The buoyancy force is equal to the weight (in Newtons) of the water displaced. The floating boat will displace its weight in water. I'm also assuming that the ball has a small volume. The floating object's displacement is also its buoyance force.

the buoyance force can be found by knowing the density of water, which is 1.00x10 to the third kg/m cubed. Multiply that by the volume of water displaced and then multiply by g, which is gravity and is a constant of 9.8 m/s squared, of 10 m/s squared for the sake of an easy number. The volume of water is the variable.

You'll need to know how much water is displaced. If you weigh the water instead of getting the volume then simply take the weight of the water times g (10). This time weight is your variable. Weighing the water displaced may be easier for your 5th grader.

I hope this helps.

Answer 3

well, the variables are the things that change in the experiment, such as the shape of the aluminum foil, or its buoyancy. Now, you can change the shape of the aluminum foil, so that variable is called the independant variable. But the buoancy of the foil filled with pennies depends on the shape of the foil, so that variable is called the dependant variable. In and experiment, you test how the independant variable affects the dependant variable.

Answer 4

There are only two variables in this experiment: (1) density of the aluminum balls and (2) buoyancy. Density may be referred to as the controlled or treatment variable, and buoyancy is the response variable.

This experiment is testing a hypothesis that buoyancy is affected by the density of an object.

The null hypothesis is that buoyancy is not affected by the density of an object. If a difference in buoyancy is found, the null hypothesis is rejected, and the experimenter concludes that density affects buoyancy.

Answer 5

Aluminum Foil Boat Experiment

Answer 6

The variable is how you store it, because it varies. The dependant is how well the popcorn pops because it depends on how you store it.

Answer 7

Read about archimedes principle:

http://en.wikipedia.org/wiki/Buoyancy#Archimedes.27_principle

These parameters are of interest:
Mass
Volume
Density

Good luck!

Answer 8

This is good

Answer 9

thank you for all the answers!