technoquest

Q Why does milk expand when it is cold?

A Milk is made mainly of water. Water has the curious property of being more dense as a liquid than as a solid. This means solid ice floats on liquid water. It also means that the ice takes up more space than the liquid and so milk expands when it freezes, pushing the top off the bottle.

Q Do identical twins have identical fingerprints?

A If the twins are monozygots (from the same egg), they will have identical fingerprints. Environmental factors and changes after birth, however, are likely to change them later.

Q Does the moon have a magnetic field? How would a compass react there?

A The moon has no overall magnetic field, but it does have local, randomly directed magnetic fields. What a compass would do would depend on where you were. In some places, it would register a field, in others it wouldn't.

Q Why does the moon keep one face turned towards us?

A It rotates on its axis once in 27 days and revolves round the earth in the same period of time. This is known as synchronous rotation, ie keeping the same face (the "near side") towards Earth.

Q Which planet has the hottest surface temperature?

A The temperature on Venus is 462OC due to its carbon dioxide atmosphere, the product of a runaway greenhouse effect.

Q How do flies land on a ceiling and take off?

A Flies turn over in flight as they approach a ceiling and hit the surface with either their front or back legs, and rotate on to the others. If they need to grip a rough surface, they use claws. If it is a smooth surface, they have sticky pads like doormats of sticky hairs with fluid on the end. To take off, they slide or peel off their feet from the surface.

Q When a limb is amputated, it often feels as if it is still there. Why?

A This bizarre phenomenon is called "phantom limb" pain. Sometimes, pain seems to come from the amputated part, which is probably due to stimulation of the stump. This happens because there are still nerves in the stump that would have continued into the leg or arm but have now been severed. Nobody is absolutely sure how it happens, but messages are still being sent along the nerves.

Q Why does hair go grey?

A A hair is a tube filled with cells and pigment with spaces between. When the hair is young, the spaces are filled with fluid and this keeps the pigment in place - your hair stays brown or blond or whatever. As we get older, our skin doesn't produce hair quite so well and they become filled with air. The pigment is lost and the hair gradually becomes white.

Questions and answers are provided by Science Line. You can use its Dial-a-Scientist service on 0345 600444.

Start your day with The Independent, sign up for daily news emails
News
FIFA President Sepp Blatter reacts during a news conference in Zurich June 1, 2011
news
News
people
Life and Style
food + drink
News
peopleKatie Hopkins criticises River Island's 'seize the day' bags for trying to normalise epilepsy
News
ebookA unique anthology of reporting and analysis of a crucial period of history
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

SThree: Trainee Recruitment Consultant

£20000 - £25000 per annum + OTE £45K YR1: SThree: At SThree, we like to be dif...

Guru Careers: Software Developer / Web Developer

£30 - 40k + Benefits: Guru Careers: A Software / Web Developer (PHP / MYSQL) i...

Guru Careers: Account Executive

£18 - 20k + Benefits: Guru Careers: An Account Executive is needed to join one...

Guru Careers: Software Developer / Software Engineer

£35 - 40k + Benefits: Guru Careers: A Software Developer / Software Engineer i...

Day In a Page

Blundering Tony Blair quits as Middle East peace envoy – only Israel will miss him

Blundering Blair quits as Middle East peace envoy – only Israel will miss him

For Arabs – and for Britons who lost their loved ones in his shambolic war in Iraq – his appointment was an insult, says Robert Fisk
Isis in Syria: The Kurdish enclave still resisting the tyranny of President Assad and militant fighters

The Kurdish enclave still resisting the tyranny of Assad and Isis

In Syrian Kurdish cantons along the Turkish border, the progressive aims of the 2011 uprising are being enacted despite the war. Patrick Cockburn returns to Amuda
How I survived Cambodia's Killing Fields: Acclaimed surgeon SreyRam Kuy celebrates her mother's determination to escape the US

How I survived Cambodia's Killing Fields

Acclaimed surgeon SreyRam Kuy celebrates her mother's determination to escape to the US
Grace of Monaco film panned: even the screenwriter pours scorn on biopic starring Nicole Kidman

Even the screenwriter pours scorn on Grace of Monaco biopic

The critics had a field day after last year's premiere, but the savaging goes on
Menstrual Hygiene Day: The strange ideas people used to believe about periods

Menstrual Hygiene Day: The strange ideas people once had about periods

If one was missed, vomiting blood was seen as a viable alternative
5 best running glasses

On your marks: 5 best running glasses

Whether you’re pounding pavements, parks or hill passes, keep your eyes protected in all weathers
Raif Badawi: Wife pleads for fresh EU help as Saudi blogger's health worsens

Please save my husband

As the health of blogger Raif Badawi worsens in prison, his wife urges EU governments to put pressure on the Saudi Arabian royal family to allow her husband to join his family in Canada
Birthplace of Arab Spring in turmoil as angry Tunisians stage massive sit-in over lack of development

They shall not be moved: jobless protesters bring Tunisia to a halt

A former North African boom town is wasting away while its unemployed citizens stick steadfastly to their sit-in
David Hasselhoff's new show 'Hoff the Record': What's it like working with a superstar?

Hanging with the Hoff

Working with David Hasselhoff on his new TV series was an education for Ella Smith
Can Dubai's Design District 'hipster village' attract the right type of goatee-wearing individualist?

Hipsters of Arabia

Can Dubai’s ‘creative village’ attract the right type of goatee-wearing individualist?
The cult of Roger Federer: What is it that inspires such obsessive devotion?

The cult of Roger Federer

What is it that inspires such obsessive devotion?
Kuala Lumpur's street food: Not a 'scene', more a way of life

Malaysian munchies

With new flights, the amazing street food of Kuala Lumpur just got more accessible
10 best festival beauty

Mud guards: 10 best festival beauty

Whether you're off to the Isle of Wight, Glastonbury or a local music event, we've found the products to help you
Unai Emery’s passion for winning and eye for a bargain keep Seville centre stage in Europe

A Different League

Unai Emery’s passion for winning and eye for a bargain keep Seville centre stage in Europe, says Pete Jenson
Amir Khan and James DeGale’s remarkable Olympic performances were just the start of an extraordinary journey - Steve Bunce

Steve Bunce on Boxing

Amir Khan and James DeGale’s remarkable Olympic performances were just the start of an extraordinary journey