# Is this a horribly ambiguous A Level Physics question?

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jedishrfu
Mentor
One funny story happened to my wife while in her MBA program. The qualifying test had a question on accounting methods and she was asked:

What was the difference between cost accounting and some other accounting scheme for the described business?

She described them both in detail highlighting their differences and got it wrong.

Later during the oral, the prof asked her about that question and told her what he really wanted was the numerical difference to which she pointed on her paper at another spot and said here it is in part B. He quickly passed her after that.

One could chalk it up to a language barrier as she was not a native speaker of English but I figured it was more incumbent on the professor to have seen that his question was ambiguous and that after having seen her answer he should have realized that and should not have marked off for it.

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jedishrfu
Mentor
Even lawyers do this in contracts in order to avoid confusion unless of course they want to confuse.

sysprog
Even lawyers do this in contracts in order to avoid confusion unless of course they want to confuse.
Many state and federal laws in the US begin with a 'definitions' section.

I think that would be a good standard practice for important standardized tests.

Although providing precise definitions for such terms as 'energy', 'force', and 'velocity' would be like providing crib notes, the multiple choice tests could have a general definitions statement saying that definitions for terms not defined in the question or test glossary, that are used differently in different standard texts, and are used in the question, should be resolved in favor of the definition that allows exactly one of the answers to be correct. If one standard definition led to one answer, and another to a different answer, that would strongly indicate a fault in the test.

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haruspex
Homework Helper
Gold Member
the marking scheme forbade the term "rate of acceleration"
Because acceleration already is a rate
That does not make "rate of acceleration" wrong.
There is no scientifically defined meaning to the expression "rate of X". Rate of change of X is defined, in terms of X and time, but not rate of X. Rate of change of acceleration would be the third derivative.

The only accepted usage of "rate of X", where X is a quantity rather than a delta to a quantity, is vernacular, so should be evaluated in that context. We do not say "rate of speed", but we do say rate of pouring, rate of setting, rate of acceleration... In each case, the X implies a change in something and the "rate" is the rate of that change. In the specific case of acceleration, the implied change is in velocity, so rate of acceleration just means rate of change of velocity.

ChrisXenon, sysprog and jedishrfu
Mark44
Mentor
That does not make "rate of acceleration" wrong.
There is no scientifically defined meaning to the expression "rate of X". Rate of change of X is defined, in terms of X and time,
You're sort of making my point. "Rate of acceleration" is very sloppy, so in an exam where the precise use of language is important, "rate of acceleration" is IMO wrong.
I said this in post #37:
"Rate of change," is more precisely phrased as "rate of change of one variable with respect to another."
If you omit the "with respect to another variable part," the meaning is only implied, and therefore not as clear as it could be or should be.

sysprog and jedishrfu
We all know that misuse of language is not uncommon; I think that ordinary understanding corrects some of the sloppiness of ordinary language; I agree with those who have opined here to the effect that problem posers are among those who should strive for non-misuse, and non-sloppy use, of language.

"the suspect was travelling at a high rate of speed"
"what was he suspected of?"
"travelling at a high rate of speed"

How can such reporting and responding be 'justified'?

The OED lists all definitions for a given word, so relying on it alone might not result in an unambiguous meaning.
A short list of key words and what they mean in the context of the exam can reduce ambiguity.
One funny story happened to my wife while in her MBA program. The qualifying test had a question on accounting methods and she was asked:

What was the difference between cost accounting and some other accounting scheme for the described business?

She described them both in detail highlighting their differences and got it wrong.

Later during the oral, the prof asked her about that question and told her what he really wanted was the numerical difference to which she pointed on her paper at another spot and said here it is in part B. He quickly passed her after that.

One could chalk it up to a language barrier as she was not a native speaker of English but I figured it was more incumbent on the professor to have seen that his question was ambiguous and that after having seen her answer he should have realized that and should not have marked off for it.
In my view, this is a no-brainer. The question-setter is entirely at fault and - being in the position where he gets to set questions in exams - shuold have known far better.

DEvens
Even lawyers do this in contracts in order to avoid confusion unless of course they want to confuse.
What lawyers do, in my view, is very far from what ought to be done by anyone.

This thread has been interesting and somehwt helpful for me, but I'm struggling to form an overall view of your opinions. It would be helpful to me, to be able to say N% of those who responded felt the questions/marking schemes examined were Perfect/Imperfect-but-serviceable/Unacceptably poor. I can't see a poll feature in the forum - does anyone know of a good way to get this summary here?

jedishrfu
Mentor
Truthfully, a poll isn't going to help your students. Basically you need to adapt or extend your tutoring in a way that lets the student make a best guess at the meaning of the words in the problem so as to get the best possible outcome in the test. The test isn't going to change because of the poll.

Its a lot like a soccer game with two equally matched teams. Its the little mistakes that add up to create the final outcome and you as a coach can only do so much. In this case, it's your students against the test developers only the ref is on their side** and the student must make the best of it.

** note 1: their is used ambiguously here although we should know it refers to the test developers.

** note 2: by being on their side, I mean the test developers are the ones who provide the questions (ambiguous or not) and the answers right or wrong (we hope right) and the student's score is based on that.

** note 3: because of the small level of uncertainty, its hard to always get a perfect score and the coach who trains them well shouldn't be blamed.

Hang in there and teach your students well (I know it sounds like a Crosby Stills and Nash song lyric)

** note 4: Crosby Stills and Nash song

Mark44
Mentor
From the OP:
For example they maintain that the word "rate" implies an increasing quantity, whereas I believe that "rate of pay" simply means how much you get paid. They say that "acceleration" will not do when a body is decelerating whereas I think that "deceleration" is an acceleration with a negative value and that all decelerations are accelerations.
As used in mathematics and physics textbooks, "rate" is a ratio that implies a change in two quantities. A decent mathematics or physics textbook would never use the phrase "rate of pay" unless the problem involved salaries that were increasing or decreasing over time.

With regard to acceleration/deceleration, if an object's velocity is decreasing and the available options describing the situation were these two choices :
a) the object is accelerating,
b) object is decelerating,
the first choice would be wrong.

sysprog
Mark44
Mentor
We're now at 62 posts for this thread. Seems like a good place to end it.