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# Viz tie break question, hard sums.

Tue 20 Oct, 2020 04:23 pm
I’m an avid reader of the British satirical comic Viz. My avatar is one of the character, Roger Mellie, the man on the telly.

Viz is a parody of British comics and the tabloid press, it’s a mixture of school boy lavatory humour and lofty intellectualism.

The Christmas quiz is a prime example, the prize is a chance to win one of thirty annuals worth about ten pounds. There is a ridiculously easy word search and another simple spot which Viz character has been turned into a frog by the ghost of Paul Daniels. Then there’s the tie break question, printed in full. For those of you good at sums enjoy.

A Marks and Spencer tie is made from polypropylene and is 2.2mm thick and has a width of 42mm at its narrowest point.

Assuming the breaking strain of the material is 23.873kgm*, what is the force in Newtons required to cause the neckwear to snap on the moon?

Assume the acceleration due to gravity on Earth is 9.81ms* and that the radius of the moon is 1737.1km and its mass is 1/80 that of Earth.

* each of the above figures is to the power of minus 2. Sorry I can’t post it on my iPad.

I don’t need to know the answer because the competition is on trust. I just have to say I’ve done it. This is what the entry form says.

Post the completed entry form or email a photograph of it to the address on the left. Just this form will do, don’t bother sending the completed word search or frog puzzle- they’ll just clog up our letterbox or email inbox and we don’t bother checking to see if they’ve been completed correctly anyway. You might not have better things to do than enter these competitions, but we’ve certainly got better things to do than mark them. And the truth is we trust you. We do. Name one other magazine that trusts its readers like that. You can’t. There aren’t any. Simply tick this box [] to confirm that you have completed the puzzle(s) correctly. Ticking the box without completing the puzzles correctly constitutes a lie for which you could be cast into the flames of hell for all eternity.
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Sturgis

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Tue 20 Oct, 2020 04:31 pm
@izzythepush,
How bad could those flames be? Have you been to the U.S. in the last few months? Between the Covid-19, the Orange Blob, along with the pod-people Republicans of both Houses, flames of Hell looks rather tame in comparison.
izzythepush

1
Tue 20 Oct, 2020 04:44 pm
@Sturgis,
Don’t be so sure.

They had a cartoon strip about a kid with his own gateway to damnation. A lot of the punishments involved being in close proximity to Jeremy Clarkson.
Sturgis

1
Tue 20 Oct, 2020 05:01 pm
@izzythepush,
Had no idea who Clarkson is. Seems demented. Among other things, there are a few months items on how he is selling scrotum scented candles to compete with Gwyneth Paltrow.

Please take away his travel Visa.
izzythepush

1
Tue 20 Oct, 2020 05:03 pm
@Sturgis,
I think his broadcasting licence is more of a concern.
Sturgis

1
Tue 20 Oct, 2020 05:04 pm
@izzythepush,
They should yank it post haste!
0 Replies

oralloy

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Wed 21 Oct, 2020 04:46 pm
izzythepush wrote:
hard sums

Probably not too hard. You just need to know the proper physics formulae to plug the numbers into.

Max probably knows all the formulae off the top of his head and could answer this easily.

It's been a very long time since I've thought about any of these formulae, but I might be able to wing it and do the equations without the formulae.

izzythepush wrote:
Assume the acceleration due to gravity on Earth is 9.81ms* and that the radius of the moon is 1737.1km and its mass is 1/80 that of Earth.

Did they give an assumed radius of the Earth?

I can assume 6371 kilometers, but if they are assuming a slightly different number, their end result will be slightly different.

I'm also assuming that 23.873 kg is referring to that weight under Lunar gravity (otherwise there would be no point in calculating the Lunar gravity). If the equations are supposed to be based on 23.873 kg under Earth gravity, that's going to lead to a completely different result.

Anyway:

"acceleration due to gravity on Earth is 9.81 m/s²"
"its mass is 1/80 that of Earth"

9.81 m/s² divided by 80 is 0.122625 m/s²

That's how much the Moon's gravity decreases due to its lower mass.

"the radius of the moon is 1737.1 km"
"radius of the Earth? I can assume 6371 kilometers"

6,371 squared is 40,589,641

1737.1 squared is 3,017,516.41

40,589,641 divided by 3,017,516.41 is 13.451340600994444964758286103239

That's how much the Moon's gravity increases due to its smaller radius.

0.122625 m/s² multiplied by 13.451340600994444964758286103239 is 1.6494706411969438138034848334097 m/s²

So that's the calculation for gravity on the Moon. Now onto the tie.

"2.2mm thick and has a width of 42mm"

2.2 mm multiplied by 42 mm gives the tie a cross section of 92.4 mm²

92.4 mm² divided by 1,000,000 gives the tie a cross section of 0.0000924 m²

"assuming the breaking strain of the material is 23.873 kg/m²"

23.873 kg/m² multiplied by 0.0000924 m² is 0.0022058652 kg

a mass of 0.0022058652 kg multiplied by a Lunar gravity of 1.6494706411969438138034848334097 m/s² results in a force of 0.00363850988583802470522438683275 newtons

Let me know if they have a different assumed radius for the Earth.
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izzythepush

1
Wed 21 Oct, 2020 04:48 pm
I have printed the puzzle in entirety. There’s nothing else.

I doubt they’ll be anything else this side of Christmas.
0 Replies

maxdancona

1
Wed 21 Oct, 2020 07:34 pm
@izzythepush,
It is supposed to be a trick question... but it is also bad physics.

1. The trick is that Newtons on Earth are the same as Newtons on the moon. Nothing about the acceleration gravity or the radius of either the Earth of the moon is relevant.

2. The unit of "strain" is not kgm*. Strain has no units... it is a length divided by a length.

The unit of "stress" is N/(m^2) . I assume that this is what they mean. In that case the Stress = Force / Area. But they are using Kg as a unit of Force. This is fucked up bad physics.

The area is 0.0022m * 0.042m = .0000924 m^2

So the force = Stress * Area. But they aren't giving us a stress, they are giving us a mass divided by an area, which is quite meaningless in a scientific sense.

I think what they want you to do is use F = Mg to convert a mass into a force. But this is completely bogus Physics. It doesn't mean anything.

oralloy

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Wed 21 Oct, 2020 07:39 pm
@maxdancona,
maxdancona wrote:
But they are using Kg as a unit of Force. This is fucked up bad physics.

I think they want people to calculate the force that "x amount of kilograms" would exert in the moon's gravity.
maxdancona

1
Wed 21 Oct, 2020 07:42 pm
@oralloy,
Yes. But it doesn't make any sense. For one thing, by doing this bogus mass you will come up with the impression that it will take a different amount of force to break the tie on the Moon than it will on Saturn.

That would contradict the actual result should you set up an experiment.
oralloy

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Wed 21 Oct, 2020 07:48 pm
@maxdancona,
The amount of force would be the same.

But the mass required to generate that force in a different gravitational field would be quite different.
maxdancona

1
Wed 21 Oct, 2020 08:55 pm
@oralloy,
The problem isn't asking for a mass... it is asking for a force. And there are lots of types of force that have nothing to do with a gravitational field.

The problem doesn't make sense.
oralloy

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Wed 21 Oct, 2020 11:03 pm
@maxdancona,
maxdancona wrote:
The problem isn't asking for a mass... it is asking for a force.

Yes. It is asking for a force that the moon's gravity would exert on a certain mass.

To calculate the force, you need to calculate what the mass in question is, and then calculate what force the moon's gravity would exert on that mass.
maxdancona

1
Wed 21 Oct, 2020 11:24 pm
@oralloy,
Nonsense Oralloy. It is asking for how much force is required to break the tie. But it doesn't matter.

Do you understand that a half meter long tie will have less mass than a one meter long tie? Without knowing the length of the tie, you can't possibly calculate its mass.

This question is complete nonsense.
maxdancona

1
Wed 21 Oct, 2020 11:32 pm
This reminds me of one of my favorite math questions...

If King Henry the Eighth had 5 wives. How many wives did King Henry the Sixth have?

If you give this question to high school kids (and I have) some of them will set up a ratio to solve the problem (and complain the answer isn't a whole number). This is because they are trained to multiply ratios... and so that is what they do.

Of course, the problem (and any mathematical solution) doesn't make sense.

Just because you can multiply numbers together doesn't mean the result has any meaning.
oralloy

0
Wed 21 Oct, 2020 11:33 pm
@maxdancona,
maxdancona wrote:
Nonsense Oralloy. It is asking for how much force is required to break the tie.

Yes. That is what it is asking for.

maxdancona wrote:
But it doesn't matter.
Do you understand that a half meter long tie will have less mass than a one meter long tie? Without knowing the length of the tie, you can't possibly calculate its mass.
This question is complete nonsense.

Why would we need to know the mass of the tie in order to calculate the amount of force that would break it?
maxdancona

1
Wed 21 Oct, 2020 11:35 pm
@oralloy,
In your last post you yourself said we need to calculate the mass.
oralloy

0
Wed 21 Oct, 2020 11:40 pm
@maxdancona,
Not the mass of the tie.

We need to calculate the mass that will provide weight sufficient to break the tie under the pull of lunar gravity.
0 Replies

izzythepush

1
Thu 22 Oct, 2020 01:54 am
If anyone has any problems with this they can write to letters @Viz.co.uk.

Don’t expect a serious response, it is Viz .

Although you may get a better response if you mention former Leeds United and Scotland frontman Arthur Graham and ask if they could show that picture of the bloke kissing the bird on the arse.

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