Questions and answers provided by Science Line's Dial-a-Scientist on 0345 600444

Q Does a bullet still accelerate once it has left the barrel of a gun?

No - it begins to decelerate as soon as it leaves the barrel, or even before if the barrel is long, because there is no new impulse applied. Also, a bullet fired from a gun held one metre off the ground will hit the ground at the same time as a pebble dropped from someone's hand one metre above the ground - about half a second later.

Q Why does newspaper go yellow faster than other paper?

The main components of wood are cellulose and lignin. Cellulose is long- fibred and strong - so paper remains supple over a long time. Lignin is a polymer that makes wood hard, and is acidic. When making high-quality paper, the pulp is cooked, which removes the lignin. However, the newspaper publishers' main concern is to get the news to the reader as quickly and as cheaply as possible. Thus they use the cheapest papers and the cheapest inks. As newspapers have a very short shelf life, there isn't much point in making them out of posh paper. Newspaper is made from wood that hasn't been cooked, so most of the lignin remains. This is what turns yellow on exposure to sunlight.

Q Why doesn't dew form on a car parked in a car port, although it is open on all sides?

This is because of heat loss. The car port is insulated by the roof both from excessive heat build-up during the day, and from sudden heat loss at night. So during the day, moisture-heavy air doesn't collect under the port because the air there is cooler than that around it (and so can't absorb as much moisture as warm air). At night, when the earth starts to lose heat, the car port stays at relatively the same temperature as before; so there isn't such a sharp drop in temperature, nor so much moisture in the air there. The result: dew doesn't form.

Q How much rubbish do people recycle in the UK?

Not enough. Presently we only recycle about 5 per cent of our rubbish; the rest is disposed of in landfill sites or incinerated. We are trying to recycle more, with government targets to recycle 20 per cent of domestic waste by the year 2000, and packaging regulations to be introduced this year requiring retailers to recycle a percentage of the packaging they sell. The problem with landfills is that even the normally biodegradable stuff like paper, which takes up more than half of landfills, doesn't really break down because of the lack of oxygen: even 20-year-old sausages have been found intact. We are also running out of sites for potential landfills. Rubbish often has to be taken by truck to locations miles away from where it was generated.

Q Why does jelly set when you put tinned pineapples in it, but does not set when you put fresh pineapple in it?

Raw pineapples, like figs and papayas, contain an enzyme (known as a protease) that breaks proteins down into small fragments. If raw pineapple is put in gelatin for a dessert or fruit salad, this enzyme digests the gelatin molecules and liquefies the water-protein gel. Canned pineapple has been heated, which deactivates the enzyme, and so it co-operates quite well with gelatin.

You can also visit the technoquest World Wide Web site at com/CampusWorld/pub/ScienceNet

Questions for this column can be submitted by email to

Start your day with The Independent, sign up for daily news emails
There will be a chance to bid for a rare example of the SAS Diary, collated by a former member of the regiment in the aftermath of World War II but only published – in a limited run of just 5,000 – in 2011
charity appealTime is running out to secure your favourite lot as our auction closes at 2pm today
File: James Woods attends the 52nd New York Film Festival at Walter Reade Theater on September 27, 2014
peopleActor was tweeting in wake of NYPD police shooting
Martin Skrtel heads in the dramatic equaliser
SPORTLiverpool vs Arsenal match report: Bandaged Martin Skrtel heads home in the 97th-minute
Billie Whitelaw was best known for her close collaboration with playwright Samuel Beckett, here performing in a Beckett Trilogy at The Riverside Studios, Hammersmith
people'Omen' star was best known for stage work with Samuel Beckett
ebooksA year of political gossip, levity and intrigue from the sharpest pen in Westminster
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating

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

iJobs Job Widget
iJobs General

Recruitment Genius: Telesales & Customer Service Executives - Outbound & Inbound

£7 - £9 per hour: Recruitment Genius: Are you outgoing? Do you want to work in...

Recruitment Genius: National Account Manager / Key Account Sales

£30000 - £35000 per annum: Recruitment Genius: An opportunity has arisen for a...

Recruitment Genius: Operations Manager

£30000 - £35000 per annum: Recruitment Genius: An exciting opportunity to join...

Recruitment Genius: Recruitment Consultant

£30000 - £35000 per annum: Recruitment Genius: We have an excellent role for a...

Day In a Page

Surrounded by high-rise flats is a little house filled with Lebanon’s history - clocks, rifles, frogmen’s uniforms and colonial helmets

Clocks, rifles, swords, frogmen’s uniforms

Surrounded by high-rise flats is a little house filled with Lebanon’s history
Return to Gaza: Four months on, the wounds left by Israel's bombardment have not yet healed

Four months after the bombardment, Gaza’s wounds are yet to heal

Kim Sengupta is reunited with a man whose plight mirrors the suffering of the Palestinian people
Gastric surgery: Is it really the answer to the UK's obesity epidemic?

Is gastric surgery really the answer to the UK's obesity epidemic?

Critics argue that it’s crazy to operate on healthy people just to stop them eating
Homeless Veterans appeal: Christmas charity auction Part 2 - now LIVE

Homeless Veterans appeal: Christmas charity auction

Bid on original art, or trips of a lifetime to Africa or the 'Corrie' set, and help Homeless Veterans
Pantomime rings the changes to welcome autistic theatre-goers

Autism-friendly theatre

Pantomime leads the pack in quest to welcome all
The week Hollywood got scared and had to grow up a bit

The week Hollywood got scared and had to grow up a bit

Sony suffered a chorus of disapproval after it withdrew 'The Interview', but it's not too late for it to take a stand, says Joan Smith
From Widow Twankey to Mother Goose, how do the men who play panto dames get themselves ready for the performance of a lifetime?

Panto dames: before and after

From Widow Twankey to Mother Goose, how do the men who play panto dames get themselves ready for the performance of a lifetime?
Thirties murder mystery novel is surprise runaway Christmas hit

Thirties murder mystery novel is surprise runaway Christmas hit

Booksellers say readers are turning away from dark modern thrillers and back to the golden age of crime writing
Anne-Marie Huby: 'Charities deserve the best,' says founder of JustGiving

Anne-Marie Huby: 'Charities deserve the best'

Ten million of us have used the JustGiving website to donate to good causes. Its co-founder says that being dynamic is as important as being kind
The botanist who hunts for giant trees at Kew Gardens

The man who hunts giants

A Kew Gardens botanist has found 25 new large tree species - and he's sure there are more out there
The 12 ways of Christmas: Spare a thought for those who will be working to keep others safe during the festive season

The 12 ways of Christmas

We speak to a dozen people who will be working to keep others safe, happy and healthy over the holidays
Birdwatching men have a lot in common with their feathered friends, new study shows

The male exhibits strange behaviour

A new study shows that birdwatching men have a lot in common with their feathered friends...
Diaries of Evelyn Waugh, Virginia Woolf and Noël Coward reveal how they coped with the December blues

Famous diaries: Christmas week in history

Noël Coward parties into the night, Alan Clark bemoans the cost of servants, Evelyn Waugh ponders his drinking…
From noble to narky, the fall of the open letter

From noble to narky, the fall of the open letter

The great tradition of St Paul and Zola reached its nadir with a hungry worker's rant to Russell Brand, says DJ Taylor
A Christmas ghost story by Alison Moore: A prodigal daughter has a breakthrough

A Christmas ghost story by Alison Moore

The story was published earlier this month in 'Poor Souls' Light: Seven Curious Tales'