qwertyuiop1234567890 wrote:Astroknight wrote:qwertyuiop1234567890 wrote:Are there any penalties for wrong concepts in your experiment?
I believe there's a huge point penalty for not doing your experiment on topic.
I meant if the experiment is on topic, but the idea of your experiment isn't correct (scientifically). For example, if we had to conduct an experiment on Newton's Second Law, f=ma, so we tested how the mass of a toy car affects its acceleration as it rolls down a ramp and travels a certain distance (that is the same for all levels of IV). The concept is wrong, as the mass of the car also affects the force, so none of the variables in the equation are actually constant, but the experiment is still on topic (kinda...).
Are there any point deductions for that kind of error? If so, how many points?
Hmm...I think it mostly depends on the way you word it. If my team were to do this experiment, here's how I'd write up the Statement and Hypothesis.
Statement of Problem:
How does increasing the mass of an object (I.V.) affect the distance it rolls, when rolled down a ramp?
Hypothesis:
We hypothesize that as the mass of the object increases, the distance it rolls will increase as well. For this particular experiment...blah blah blah...
Our rationale for this hypothesis is as follows:
As we increase the mass of the object, the downwards force exerted will increase as well; this is given in Newton's 2nd law, F = ma. When the force is increased, the acceleration of the object will increase, thus leading to greater momentum. As the momentum is increased, the distance the object will have to cover to dissipate its kinetic energy through friction will also increase. Therefore, as the mass of the object increases, the distance it rolls will also increase.
Here's the thing: you are only physically changing one thing (mass). Hence, your IV should be mass. However, you need to admit in your rationales, reasons, etc. throughout the paper what factors the mass is actually increasing, and why that affects the DV. In this case, the increased mass leads to an increased force, thus giving a greater acceleration, which gives a greater momentum. This, in turn, gives a larger 'distance rolled' which is the only thing you can really measure in a short lab like this one.
After doing an experiment like this one, you could stick in your "applications & recommendations" that in future experiments, you could try using a force meter to directly measure the force...etc.
I'm no expert on this; I'm just a B div. student, so you don't have to take my word for it--I'm not the most authoritative source you'll get.
I hope this helps, though!!
