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Polar trader
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THE LAST WORD Polar trader
example, is higher than it would otherwise be because of the large mass of water contained in glaciers. Further minor short-term fluctuations in apparent gravitational acceleration occur because of the relative motion of the sun and moon. The Earth’s spin reduces this acceleration by about 0.3 per cent at the equator, compared with the poles. On top of this, the bulge of the planet at the equator means that objects here are further from Earth’s centre than they are at the poles, giving another reduction of
0.2 per cent. An object will n If you want to get rid of therefore weigh about 0.5 per something, you can use a cent more at the poles. chemical, physical or biological Mexico City is at an elevation agent – or you can provide a of more than 2000 metres, which different environment that pushes it still further from Earth’s it prefers. Some gardeners use sacrificial centre. However, any additional planting of nasturtiums to attract effect is cancelled out by the fact aphids and thus protect their that Mexico is still some distance prized plants, rather than using from the equator. pesticides. Aphids can then be We can thus estimate that physically removed from the 1000 tonnes of gold at the poles would reduce to a weight of nasturtiums, or the most infected 995 tonnes at the equator. So in theory, a sizeable profit could be “Limescale is deposited on the steel mesh because made if you were to buy at the it has more nucleation equator and sell at the poles. sites than the kettle” However, in practice the cost of transportation and security plant parts can be destroyed, would be prohibitive. And the leaving the rest to carry on laws of supply and demand the good work. suggest that you wouldn’t get In a similar manner, limescale a good price when penguins is deposited preferentially on the or polar bears are the only stainless steel mesh ball because customers. In addition, gold the mesh has far more nucleation bullion is usually cast in ingots sites than the kettle. These sites of a certified mass – so unless are discrete points, such as you could persuade your microscopic scratches, where customer to buy on the basis of the crystallisation of limescale the values on your own scales, (mostly calcium carbonate) starts. you would be in trouble. The mesh ball won’t capture all Simon Iveson the deposited limescale, but it School of Engineering can be periodically soaked in University of Newcastle vinegar to dissolve the build-up New South Wales, Australia and then reused. Don’t be tempted to use cheap wire wool bought in hardware Fur-up ball stores. This will corrode and the I live in a hard water area and use rust will make your tea and coffee a stainless steel mesh ball in my browner than usual. kettle to stop it “furring up”. David Muir The steel mesh traps the scale that Science Department would otherwise form inside my Portobello High School kettle. How does it work? Edinburgh, UK
The writers of answers that are published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Please include a daytime telephone number and an email address if you have one. New Scientist retains total editorial control over the published content. Reed Business Information Ltd reserves all rights to reuse all question and answer material that has been
submitted by readers in any medium or in any format and at any time in the future. Send questions and answers to The Last Word, New Scientist, 110 High Holborn, London WC1V 6EU, UK, by email to [email protected] or visit www.newscientist.com/topic/lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
If I bought 1000 tonnes of gold bullion in Antarctica and sold it in Mexico at the same price per kilogram, would I make a loss? Surely the consignment would be lighter at the equator than the poles because it is spinning faster?
n Gravitational acceleration does indeed vary slightly over Earth’s surface, partly through a combination of the planet being oblate (not perfectly spherical) and variations in the forces alluded to in the question. There are also more localised contrasts, caused by differences in rock density and large-scale topographical features – the sea level around Greenland, for
“We can estimate that 1000 tonnes of gold at the poles would reduce to 995 tonnes at the equator”
This week’s questions Revolving core
I keep reading about how every so often, Earth’s north and south magnetic poles “flip”. How long does it take for this to happen? Moments or years? And does the magnetosphere “turn off” when this change is taking place? Or is it more like turning a bar magnet through 180 degrees, with the poles moving across the planet’s surface and passing through the equator? Geoffrey Clark Douglas, Isle of Man Real feel
In the summer, meteorologists always warn that it will feel hotter because of the humidity (the “real feel” temperature). In contrast, humidity seems to exacerbate the feeling of cold in the winter. At what point does humidity cause the ambient temperature to feel hotter or cooler? Deborah Fenker New York, US Laundry stiffener
To do our bit for the planet, we have been hanging our washing on a line in the back garden rather than using our electric tumble dryer. Thicker materials such as bath towels and socks are hard and abrasive when dried on the line, in comparison to the soft and fluffy feel of the tumble-dried versions. Why does this happen? Ronan Tierney Enniscorthy, Ireland
Question Everything The latest book of science questions: unpredictable and entertaining. Expect the unexpected Available from booksellers and at newscientist.com/questioneverything
THE LAST WORD Polar trader
example, is higher than it would otherwise be because of the large mass of water contained in glaciers. Further minor short-term fluctuations in apparent gravitational acceleration occur because of the relative motion of the sun and moon. The Earth’s spin reduces this acceleration by about 0.3 per cent at the equator, compared with the poles. On top of this, the bulge of the planet at the equator means that objects here are further from Earth’s centre than they are at the poles, giving another reduction of
0.2 per cent. An object will n If you want to get rid of therefore weigh about 0.5 per something, you can use a cent more at the poles. chemical, physical or biological Mexico City is at an elevation agent – or you can provide a of more than 2000 metres, which different environment that pushes it still further from Earth’s it prefers. Some gardeners use sacrificial centre. However, any additional planting of nasturtiums to attract effect is cancelled out by the fact aphids and thus protect their that Mexico is still some distance prized plants, rather than using from the equator. pesticides. Aphids can then be We can thus estimate that physically removed from the 1000 tonnes of gold at the poles would reduce to a weight of nasturtiums, or the most infected 995 tonnes at the equator. So in theory, a sizeable profit could be “Limescale is deposited on the steel mesh because made if you were to buy at the it has more nucleation equator and sell at the poles. sites than the kettle” However, in practice the cost of transportation and security plant parts can be destroyed, would be prohibitive. And the leaving the rest to carry on laws of supply and demand the good work. suggest that you wouldn’t get In a similar manner, limescale a good price when penguins is deposited preferentially on the or polar bears are the only stainless steel mesh ball because customers. In addition, gold the mesh has far more nucleation bullion is usually cast in ingots sites than the kettle. These sites of a certified mass – so unless are discrete points, such as you could persuade your microscopic scratches, where customer to buy on the basis of the crystallisation of limescale the values on your own scales, (mostly calcium carbonate) starts. you would be in trouble. The mesh ball won’t capture all Simon Iveson the deposited limescale, but it School of Engineering can be periodically soaked in University of Newcastle vinegar to dissolve the build-up New South Wales, Australia and then reused. Don’t be tempted to use cheap wire wool bought in hardware Fur-up ball stores. This will corrode and the I live in a hard water area and use rust will make your tea and coffee a stainless steel mesh ball in my browner than usual. kettle to stop it “furring up”. David Muir The steel mesh traps the scale that Science Department would otherwise form inside my Portobello High School kettle. How does it work? Edinburgh, UK
The writers of answers that are published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Please include a daytime telephone number and an email address if you have one. New Scientist retains total editorial control over the published content. Reed Business Information Ltd reserves all rights to reuse all question and answer material that has been
submitted by readers in any medium or in any format and at any time in the future. Send questions and answers to The Last Word, New Scientist, 110 High Holborn, London WC1V 6EU, UK, by email to [email protected] or visit www.newscientist.com/topic/lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
If I bought 1000 tonnes of gold bullion in Antarctica and sold it in Mexico at the same price per kilogram, would I make a loss? Surely the consignment would be lighter at the equator than the poles because it is spinning faster?
n Gravitational acceleration does indeed vary slightly over Earth’s surface, partly through a combination of the planet being oblate (not perfectly spherical) and variations in the forces alluded to in the question. There are also more localised contrasts, caused by differences in rock density and large-scale topographical features – the sea level around Greenland, for
“We can estimate that 1000 tonnes of gold at the poles would reduce to 995 tonnes at the equator”
This week’s questions Revolving core
I keep reading about how every so often, Earth’s north and south magnetic poles “flip”. How long does it take for this to happen? Moments or years? And does the magnetosphere “turn off” when this change is taking place? Or is it more like turning a bar magnet through 180 degrees, with the poles moving across the planet’s surface and passing through the equator? Geoffrey Clark Douglas, Isle of Man Real feel
In the summer, meteorologists always warn that it will feel hotter because of the humidity (the “real feel” temperature). In contrast, humidity seems to exacerbate the feeling of cold in the winter. At what point does humidity cause the ambient temperature to feel hotter or cooler? Deborah Fenker New York, US Laundry stiffener
To do our bit for the planet, we have been hanging our washing on a line in the back garden rather than using our electric tumble dryer. Thicker materials such as bath towels and socks are hard and abrasive when dried on the line, in comparison to the soft and fluffy feel of the tumble-dried versions. Why does this happen? Ronan Tierney Enniscorthy, Ireland
Question Everything The latest book of science questions: unpredictable and entertaining. Expect the unexpected Available from booksellers and at newscientist.com/questioneverything