Key skills: weight vs. mass Watch

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Chris Howells
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Hi,

I sat the Key Skills Application of Number paper today, and as somebody who does physics and
mechanics was, erm, slightly concerned to be told, in one of the questions, something along the
lines of "has a weight of 2.5g per
cm3. Calculate the weight".

So, it seems that the person who set the paper didn't have a clue of the difference between
mass and weight. Is this to be expected? It's surely mis-leading for people doing
physics/mechanins, at least.

Would I have lost the marks if I had been pedantic and really attempted to calculate the weight,
rather than the mass which is what I think they were looking for?

--
Cheers, Chris Howells -- [email protected], [email protected] Web: http://chrishowells.co.uk,
PGP key: http://chrishowells.co.uk/pgp.txt KDE: http://www.koffice.org, http://edu.kde.org,
http://usability.kde.org
Peter Lloyd
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"Chris Howells" <[email protected]> wrote:
[q1]> Would I have lost the marks if I had been pedantic and really attempted to calculate the weight,[/q1]
[q1]> rather than the mass which is what I think they were looking for?[/q1]

Such fun. I sat the application of number paper last year and I seem to remember doing a couple of
questions two ways - once the way i felt they wanted it done, and once the way I felt the question
asked for! [Annotating each method with my reasons for doing it that way] I'm afraid I can't
remember specific examples but I had a good laugh with my maths teacher afterwards. Though I do
remember I passed - as did everyone else who took it (key skills), bar one person doing
communication.

HTH

Peter
Rikki Prince
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"Chris Howells" <[email protected]> wrote in message news:[email protected]...
[q1]> Hi,[/q1]
[q1]>[/q1]
[q1]> I sat the Key Skills Application of Number paper today, and as[/q1]
somebody who
[q1]> does physics and mechanics was, erm, slightly concerned to be told,[/q1]
in one
[q1]> of the questions, something along the lines of "has a weight of 2.5g[/q1]
per
[q1]> cm3. Calculate the weight".[/q1]

You said weight twice?! Did you mean density? I'm sure at GCSE Physics (which is the presumed level
of knowledge needed for level 3 KS isn't it?) you should know the difference between weight and
mass, so maybe it was a combined question - asking you to calculate both the mass (knowing the
density and volume) and then the weight (multiplying by
9.8)?

Rikki
Gene Nygaard
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Chris Howells <[email protected]> wrote in message news:<[email protected]>...
[q1]> Hi,[/q1]
[q1]>[/q1]
[q1]> I sat the Key Skills Application of Number paper today, and as somebody who does physics and[/q1]
[q1]> mechanics was, erm, slightly concerned to be told, in one of the questions, something along the[/q1]
[q1]> lines of "has a weight of 2.5g per[/q1]
[q1]> cm3. Calculate the weight".[/q1]
[q1]>[/q1]
[q1]> So, it seems that the person who set the paper didn't have a clue of the difference between mass[/q1]
[q1]> and weight. Is this to be expected? It's surely mis-leading for people doing physics/mechanins,[/q1]
[q1]> at least.[/q1]

What do you want to know the weight of, and why?

How do you measure the weight if you are buying bananas--in what units?

What's this silly exception in U.K. metrication laws, now in the 21st century, for continued use of
one of the units in the troy system of weights, the troy ounce, even though Great Britain outlawed
the pound on which those ounces are based back in the 19th century?

If a bar of gold has a weight of 401.23 troy ounces, how much is that in the International
System of Units?

Here's something I don't know the answer to--in what units do most people in the U.K. express their
body weight? What are the second most common units there?

[q1]> Would I have lost the marks if I had been pedantic and really attempted to calculate the weight,[/q1]
[q1]> rather than the mass which is what I think they were looking for?[/q1]

You ought to.

Gene Nygaard
Richard Magrath
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Chris Howells <[email protected]> wrote in message news:<[email protected]>...
[q1]> Hi,[/q1]
[q1]>[/q1]
[q1]> I sat the Key Skills Application of Number paper today, and as somebody who does physics and[/q1]
[q1]> mechanics was, erm, slightly concerned to be told, in one of the questions, something along the[/q1]
[q1]> lines of "has a weight of 2.5g per[/q1]
[q1]> cm3. Calculate the weight".[/q1]
[q1]>[/q1]
[q1]> So, it seems that the person who set the paper didn't have a clue of the difference between mass[/q1]
[q1]> and weight. Is this to be expected? It's surely mis-leading for people doing physics/mechanins,[/q1]
[q1]> at least.[/q1]
[q1]>[/q1]
[q1]> Would I have lost the marks if I had been pedantic and really attempted to calculate the weight,[/q1]
[q1]> rather than the mass which is what I think they were looking for?[/q1]

Yes, but isn't the joy of physics partly learning (and being confused by) the new, more specific for
words? Where I found this *really* perplexing was in the stuff on stress, strain and Young's modulus
in AS physics - in theory one of the easiest parts of the syllabus (only about three simple
calculations needing to be memorised), the problem lay in the vocabulary used. It was really hard
getting out of the habit of using "strong" and "tough", and "weak" and "fragile" interchangably,
when this would be technically incorrect in the exam.

BTW, weight is the one measured in Newtons (and equalling mass x g) isn't it?

Rich
Rikki Prince
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"Gene Nygaard" <[email protected]> wrote in message
news:[email protected]...
[q1]> Chris Howells <[email protected]> wrote in message[/q1]
news:<[email protected]>... <snip>
[q1]> Here's something I don't know the answer to--in what units do most people in the U.K. express[/q1]
[q1]> their body weight? What are the second most common units there?[/q1]

Haven't done a survey, but I still use stones, pounds and ounces, though official type people use
kilograms. I couldn't tell you which most people use. Due to stubborness, I'd guess most people
still use stones etc, but maybe enough people (children being taught kg, people who use gyms with kg
scales, and people who have given up fighting the EU) use KG to be over 50% of the UK.

Referring to the original question, it must be noted that mass and weight are different. From a
pedantic physicist's point of view weight is actually the physical force on a body by the Earth (or
other local large body).

[q2]> > Would I have lost the marks if I had been pedantic and really[/q2]
attempted to
[q2]> > calculate the weight, rather than the mass which is what I think[/q2]
they were
[q2]> > looking for?[/q2]
[q1]>[/q1]
[q1]> You ought to.[/q1]

Why? You shouldn't lose *any* marks for correctly answering the question they *actually* set.
Doesn't matter what they meant - you have to answer the question they set.

Rikki
Chris Howells
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Peter Lloyd wrote:

[q1]> Such fun. I sat the application of number paper last year and I seem to remember doing a couple of[/q1]
[q1]> questions two ways - once the way i felt they wanted it done, and once the way I felt the question[/q1]
[q1]> asked for![/q1]

I didn't really find that to be honest -- thankfully it was nice and easy though. In fact, I'm
pretty sure GCSE maths was harder.

I did the communication paper today which was very much like GCSE english.

*yawn*

Well I've got the IT paper in few days. Shouldn't be too hard except that I only use Windoze to play
games these days and it must be about two years since I've used Word/Excel to do anything serious.

[q1]> [Annotating each method with my reasons for doing it that way] I'm afraid I can't remember[/q1]
[q1]> specific examples but I had a good laugh with my maths teacher afterwards. Though I do remember I[/q1]
[q1]> passed - as did everyone else who took it (key skills), bar one person doing communication.[/q1]

Yeah, I might ask a few of my teachers what they thought of the paper.

--
Cheers, Chris Howells -- [email protected], [email protected] Web: http://chrishowells.co.uk,
PGP key: http://chrishowells.co.uk/pgp.txt KDE: http://www.koffice.org, http://edu.kde.org,
http://usability.kde.org
Chris Howells
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Rikki Prince wrote:

[q1]> Haven't done a survey, but I still use stones, pounds and ounces, though official type people use[/q1]
[q1]> kilograms. I couldn't tell you which most people use. Due to stubborness, I'd guess most people[/q1]
[q1]> still use[/q1]

I use a mixture of imperial and metric depending on the situation. For example I was of course
taught metric and school, but I'm not quite sad enought to go up to the bar and say "I'd like 568ml
of xyz please" :P

[q1]> Referring to the original question, it must be noted that mass and weight are different. From a[/q1]
[q1]> pedantic physicist's point of view weight is actually the physical force on a body by the Earth[/q1]
[q1]> (or other local large body).[/q1]

Exactly my point.

[q1]> Why? You shouldn't lose *any* marks for correctly answering the question they *actually* set.[/q1]
[q1]> Doesn't matter what they meant - you have to answer the question they set.[/q1]

Indeed. However, I felt that doing what I felt they expected would be safer than being pedantic.
Their inability to distinguish between weight and mass hardly makes me feel confident that I would
have received the marks if I had calculated the weight.

I'm just wondering though -- if they had used 'mass', would it have confused the people that _don't_
study physics/mechanics?

--
Cheers, Chris Howells -- [email protected], [email protected] Web: http://chrishowells.co.uk,
PGP key: http://chrishowells.co.uk/pgp.txt KDE: http://www.koffice.org, http://edu.kde.org,
http://usability.kde.org
John Porcella
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[q1]> Referring to the original question, it must be noted that mass and weight are different. From a[/q1]
[q1]> pedantic physicist's point of view weight is actually the physical force on a body by the Earth[/q1]
[q1]> (or other local large body).[/q1]

Strangely, I asked my maths tutor what the difference was between mass and weight only yesterday,
and he told me that mass was a vector (I think that is what he said) and weight was the effect of
gravity on a mass. In other words, Mass x Gravity = Weight. Hence, a body in deep space will have
mass but no weight if there is no gravity nearby.

--
MESSAGE ENDS. John Porcella
Rikki Prince
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"Richard Magrath" <[email protected]> wrote in message
news:[email protected]... <snip>
[q1]> BTW, weight is the one measured in Newtons (and equalling mass x g) isn't it?[/q1]

Yup

Rikki
Rikki Prince
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"John Porcella" <[email protected]> wrote in message
news:[email protected]...
[q2]> > Referring to the original question, it must be noted that mass and weight are different. From a[/q2]
[q2]> > pedantic physicist's point of view[/q2]
weight
[q2]> > is actually the physical force on a body by the Earth (or other[/q2]
local
[q2]> > large body).[/q2]
[q1]>[/q1]
[q1]> Strangely, I asked my maths tutor what the difference was between[/q1]
mass and
[q1]> weight only yesterday, and he told me that mass was a vector (I[/q1]
think that

Hmm, I didn't think mass was a vector (though I may be wrong) as I thought that was the point - mass
is a scalar description, whereas weight is a force, with direction towards the centre of the
attracting body...

Rikki
John Porcella
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"Rikki Prince" <[email protected]> wrote in message
news:[email protected]...
[q1]> "John Porcella" <[email protected]> wrote in message[/q1]
[q1]> news:[email protected]...[/q1]
[q3]> > > Referring to the original question, it must be noted that mass and weight are different. From[/q3]
[q3]> > > a pedantic physicist's point of view[/q3]
[q1]> weight[/q1]
[q3]> > > is actually the physical force on a body by the Earth (or other[/q3]
[q1]> local[/q1]
[q3]> > > large body).[/q3]
[q2]> >[/q2]
[q2]> > Strangely, I asked my maths tutor what the difference was between[/q2]
[q1]> mass and[/q1]
[q2]> > weight only yesterday, and he told me that mass was a vector (I[/q2]
[q1]> think that[/q1]
[q1]>[/q1]
[q1]> Hmm, I didn't think mass was a vector (though I may be wrong) as I thought that was the point -[/q1]
[q1]> mass is a scalar description, whereas weight is a force, with direction towards the centre of the[/q1]
[q1]> attracting body...[/q1]
[q1]>[/q1]
[q1]>[/q1]
[q1]> Rikki[/q1]

That would appear to be better!

Thanks.

--
MESSAGE ENDS. John Porcella
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