You will have 25 minutes to answer a single experimental design question worth 12 points in the FRQ portion of the AP Physics 1 exam.
You will have 25 minutes to answer a single experimental design question worth 12 points in the FRQ portion of the AP Physics 1 exam. Read the question to determine the relationship being posed, list the quantities to be measured (2:47), develop a procedure to collect that data (4:48), and explain how you would analyze the data collected. (5:46) Good luck!
Question of the Day (7:42) When asked to provide a procedure for an experiment that you have created, what should you avoid doing?
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Hi and welcome to the APsolute RecAP: Physics 1 Edition. Today’s episode will focus on strategies associated with answering the experimental design free response question.
Let’s Zoom out
One of the five free response questions you will be asked to answer is to design an experiment targeted at answering a testable question posed on the exam. By knowing a few things and practicing this question type, you can often improve your score. The College Board expects that this question should take approximately 25 minutes, and will be worth 12/45 of the FRQ points.
Let’s Zoom in:
Ok, so what will the question look like? The question can actually take a few different forms, but generally there are three main tasks students are asked to complete: identify the quantities to be measured, describe a procedure to collect the data for those quantities, and finally to organize and analyze the data collected to answer the question posed. To demonstrate these, let’s use an example question.
A student believes that the coefficient of friction between a wooden block and the lab table is dependent upon the block’s velocity. First, list the quantities, associated symbols, and lab equipment that would be used to measure in your experiment. Your goal here is to list only the quantities you would need to measure in order answer the question posed. It sometimes helps to lay out the experiment that you would conduct in order to answer the question, and then determine what you would need to measure. For example, to answer the question posed you would need to know the velocity of the block and you would need to know the coefficient of friction. An experiment that could measure both of these could involve sliding a block along the table with only friction acting to slow it down to rest. You could release the block at faster and faster initial velocities and then record the distance and time it slides to rest. Knowing that info, you could determine the negative acceleration of the block and then the net force of friction acting on the block. This frictional force with the normal force could be used to determine the coefficient of friction.
So, we need to measure all of this. How could the velocity be measured? The velocity of the block could be measured using either a motion detector, video analysis, or a measuring tape with a stopwatch. I am sure there are other ways you could come up with, but these are the most common. We also needed to know the negative acceleration of the block and the block’s mass in order to determine the net force. For acceleration, we could just use the same equipment we used for the velocity. For mass we could use a digital balance or a spring scale. We also need to know the normal force to calculate the coefficient of friction, our reading for mass on the balance would be sufficient to help here since normal force equals gravitational force on a level surface. That’s all of the quantities necessary. We would complete the table and add some symbols like “m” for mass and “t” for time etc.
Now it is time to plan the procedure. We want to be sure to do a variety of trials to reduce measurement uncertainty and error. More importantly we need to state that we will need to VARY the velocity at which we slide the wooden block. We will record the speed and displacement of the block while it slides to rest. We will complete 5 trials of different speeds. The mass of the block will be measured and recorded. We will keep the mass of the block constant throughout. That’s it! That’s enough! We could write the procedure in paragraph form, or use a bulleted list. Whatever you choose, don’t fill it up with silly steps like “obtain your ruler from your teacher.” And, definitely DO NOT talk about calculations that you would do. That is all explained later in a different portion of the question. A procedure is a set of directions you would give someone to collect the necessary data, that’s all!
Finally, you will be asked to analyze the data collected in order to arrive at a conclusion about the hypothesis stated, “coefficient of friction is dependent upon velocity.” You could explain that you would use the velocity vs time graph to gather velocity data. As for the coefficient of friction, you would need to explain how you would calculate that quantity with your data. It could sound something like, “To find net force I would multiply the measured mass by the acceleration which I found by taking the slope of the velocity time graph I recorded with the motion detector. Then I would divide the net force which is equal to friction by the normal force which is equal to the mass times 9.8 m/s/s. I would now have my coefficient of kinetic friction. I would make a graph of velocity vs coefficient of friction. Any slope to that graph would signify that there is in fact a relationship between the velocity of the block and the coefficient of friction.” PERFECT-O. And that is how you answer an experimental design question.
To Recap…
You will have 25 minutes to answer a single experimental design question worth 12 points in the FRQ portion of the AP Physics 1 exam. Read the question to determine the relationship being posed, list the quantities to be measured, develop a procedure to collect that data, and explain how you would analyze the data collected. Good luck!
Thanks for listening to The APsolute recAP Physics 1 edition this season and good luck to all of you as you take the exam. I wish you all the best of luck. It has been a challenging year, but all of your hard work has made you a better student and a more well-rounded individual. After a year of physics, the entire world will look differently now that you get to see it through the physics tinted lenses.
Today’s Question of the Day focuses on a test taking tip outlined in this week’s episode.
Question:
When asked to provide a procedure for an experiment that you have created, what should you avoid doing?