Good morning. In a previous video I explained Qualitative and Quantitative Translation and Paragraph
Argument Short Answer questions for the AP Physics Exams. This video is about the Experimental Design
Questions. Bo, please read the quote from the AP Physics 1 Course and Exam Description.
♪ Flipping Physics ♪
“When presented with an experimental design question,
students often do not know where to start.” Oh boy, that’s not fun.
No. Yeah.
Right. I think it is good to begin by acknowledging that students often struggle
with experimental design questions. It requires designing a hypothetical experiment and that can
be intimidating. Please, heed my advice in this video and practice with as many free response
questions as you can. Did I mention I have video solutions for those in the description?
What video? Right.
Bobby, please read another quote from the Course and Exam Description.
“This question type assesses student ability to design and describe a scientific investigation,
analyze authentic laboratory data, and identify patterns or explain phenomena.”
Again, you are going to design an experiment. Often you will be asked to look at raw data,
determine how to rearrange that data in order to prove properties of physics,
and be able to recognize relationships within the data. Billy, the next quote please?
“Students must be able to justify their selection of the kind of data needed to answer the question
and then design a plan to collect that data.” Sometimes you are not provided with data,
but rather you are asked what data would need to be collected to prove physics phenomena.
And then you are asked to design an experiment that will allow for collection
of that data. … And, one last quote. Bo, please? “Students should be prepared to offer evidence,
construct reasoned arguments for their claim from the evidence, and use the
claim or explanation to make predictions.” You will also be asked to defend your choices
using logical reasoning. When you do so, please use my suggestions about Paragraph Argument
Short Answer from the video I mentioned earlier. … Let’s now talk about specifics
of AP Physics Experimental Design Questions. Let’s start with Free Response Question number
2 from the 2016 AP Physics 1 exam. Parts (a) and (b): … Now, I am not going to
read through the whole question, you can pause the video and do that if you want to. However,
I am going to point out that this problem clearly asks you to “design an experiment”. Clearly,
every one of the Experimental Design Questions will ask you to design an experiment. When you do,
please choose a lab setup and experimental design which is as simple as you can make it. The more
complicated the experimental design, the longer it will take you to describe. You do not have
time to fritter away on an AP Physics exam. Remember Bo wanted to build a potato cannon
to answer this question? Yeah, woah.
It would’ve worked and been a lot more fun than just dropping a ball, … Bobby.
Right Bo, but again. Simpler experiments are better for AP Physics Exam Experimental Design
Questions. … Okay, I definitely recommend reading all the way through part (b)
of this question before beginning to answer any part of the question.
This is typical of Experimental Design Questions. When designing the experiment,
you need to understand all the requirements of the experiment. In order to understand all the
requirements, you need to read the whole question. … And you need to think all the
way through the experiment and not rush to answer each question before answering the next question.
You need to think about answering the questions as a whole, not individually. For example, deciding
how to represent the data in a graph affects what experiment you are going to perform and what data
to collect. So, you need to think about or even determine what values are going to go on the x and
y axes of your graph as you design the experiment. … When you “describe your procedure”, please
do not include extraneous steps like “collect all lab equipment” or “sharpen my pencil” or
“meditate to clear my mind in preparation for accurate data collection”.
We always “limber up” before we do the right-hand rule!
I think that’s different. Yeah.
When describing your experimental design, you will likely be asked to draw an experimental setup and
to label the items. Please make sure you actually label the items. The AP graders will not guess
what objects you have drawn. … You may be given a list of possible lab equipment and asked to choose
which items to use. This was done on the second free response question on the 2012 AP Physics C:
Mechanics exam. … Or, like the previous Free Response Question we were talking about,
#2 from the 2016 AP Physics 1 exam, you may simply be given free rein to pick and choose whatever
equipment you would like to. Again, please remember to keep it simple. … Another possibility,
like Free Response Question #3 from the 2019 AP Physics 1 exam, is that you may be given
an apparatus and asked how to use it. … The point here is that there are a lot of possibilities for
what they might expect you to determine about lab equipment. You just need to read carefully,
and answer the questions asked. That seems like pretty obvious
advice. “Answer the questions asked.” Yeah. You might be surprised at the number of
times students do not read carefully enough and think the experiment they
are being asked to design is exactly the same as one they have seen before,
when in actuality, it is only similar to one they have seen before and they therefore lose a lot of
points simply because they are not actually answering the question which is being asked.
Ah, right. That makes sense. Read carefully. Do not make assumptions.
Chances are very good you will be required to create a graph and plot data on that graph.
When you do … label both axes and include units. … Plot the data carefully. … Pick axes scales
such that you use more than half the graph. In other words, do not plot all the data in
one corner of the graph. … When drawing the best fit line, a good approximation is to have
half the data points above and half the data points below the best fit line. …
This concept of creating a graph, plotting data, adding a best fit line, and then comparing the
slope to an accepted value is an effective way to, as mentioned in the Course and Exam Description,
“construct reasoned arguments for (your) claim from the evidence, and use the claim or
explanation to make predictions.” … You may be asked to estimate how a graph
would change based on changes to the data. And in part (c) of the second Free Response
Question on the 2016 AP Physics 1 Exam, they asked what our data would look like
if the experiment appears to violate a law of physics. So, that might happen.
In the second Free Response Question on the 2017 AP Physics 1 Exam, they gave us data
and asked us to interpret what happened and they expected us to notice that there was an
error in one of the lab group’s data. That’s kind of the reverse of what Billy just pointed out.
Very nice, yeah. You could be asked how the data will change if a part of the experiment is
changed. For example, How does doubling the mass of an object affect the data or graph?
They did that in part (d) of the Free Response Question Bobby just mentioned. … Alright, I want
to get back to the fact that I am asking you to read carefully. One thing I want you to notice,
from various exams, is “include steps necessary to reduce experimental uncertainty”. … To reduce
experimental uncertainty, not only do you need to mention performing multiple trials; you also need
to make sure you mention making adjustments to the data you are collecting. For example, you might
change the height initial, or change the initial velocity, or change the location of an object.
This request to “reduce experimental uncertainty” has appeared on several Experimental Design
Questions. … Also, I have seen “In your diagram, indicate each quantity that would be measured”.
And, if you indicated each quantity that would be measured, however, you do not put that “in your
diagram” you lose points. … When asked for each “quantity that would be measured” do not include
measuring variables which are extraneous. If you do not need to measure something,
do not measure it. When it is not necessary, writing more is actually worse for your grade. …
They may ask for “a symbol for each measurement”, in which case they need you to assign a symbol or
variable for each measurement. Theta for an angle, m for mass, delta x for displacement,
for example. They did this on the 2012 AP Physics C: Mechanics exam Free Response
Question #2. … Also, be careful of the solving for a variable “in terms of the quantities measured”.
Which is what happened in part (c) on that same free response question.
They asked for the kinetic energy final “in terms of the quantities measured in part (b)”
and many students missed that velocity final was not one of the quantities measured in part (b). …
When you are asked to explain or “justify your answer”, please make sure you do so. An answer
with no justification when they specifically ask you to “justify your answer” most likely will get
you zero points. … Lastly, if you have time, when you are done with all the free response questions,
go back and read the questions carefully to make sure you have included everything they ask for.
Again, only if you have time at the end. Like we are going to have extra time.
We might not have frittered it all away! Uh.
Right. … But how do we start? Yeah, that’s where I get stuck.
That is a good point. I would say you should start by looking at the equation sheet. The experiment
is usually about finding a relationship between variables. That means you should find equations
which have to do with the variables in the experiment. For example, if the experiment
involves testing friction, look for equations which involve friction and use that as a starting
point. If the experiment involves springs, what equations have to do with springs and the spring
constant? If the experiment involves collisions, what equations have to do with collisions?
If the experiment is about waves, what equations do we have which are about waves?
When you have identified applicable equations, you can determine which variables need to be
identified and measured. Then you can determine which lab equipment will be necessary to measure
the variables needed in the equations. And the equations should help to visualize what the graph
of the data will look like and what the slope of the best-fit line of the data will represent. … In
fact, this highlights a basic way of studying for the exam. You should look over all the equations
we have and identify what physical objects they represent. And you should do the reverse.
Look over labs and problems you have done. Identify their physical situations and objects,
and what equations are used with those objects. This will help when it comes to Experimental
Design Questions because there you are often given physical situations and you need to identify
equations which are applicable to the physical situations. … Does that help know where to start?
Absolutely! … Yeah? … Sure. Good. … I’ve included links to
all the Experimental Design Exam Questions for which I have solutions in the video description.
Hopefully those will be helpful for you. Good luck
and enjoy the AP Physics exams! Enjoy? … I will. … Uuuhh.
Thank you very much for learning with me today, I enjoyed learning with you.