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

Susan Sarandon described David Bowie as
peopleSusan Sarandon reveals more on her David Bowie romance
Arsenal supporters gather for a recent ‘fan party’ in New Jersey
sportDidier Drogba returns to Chelsea on one-year deal
Arts and Entertainment
The Secret Cinema performance of Back to the Future has been cancelled again
Life and Style
Balmain's autumn/winter 2014 campaign, shot by Mario Sorrenti and featuring Binx Walton, Cara Delevingne, Jourdan Dunn, Ysaunny Brito, Issa Lish and Kayla Scott
fashionHow Olivier Rousteing is revitalising the house of Balmain
Arts and Entertainment
Christian Grey cradles Ana in the Fifty Shades of Grey film
filmFifty Shades of Grey trailer provokes moral outrage in US
BBC broadcaster and presenter Evan Davis, who will be taking over from Jeremy Paxman on Newsnight
peopleForget Paxman - what will Evan Davis be like on Newsnight?
Life and Style
fashionCustomer complained about the visibly protruding ribs
The new dawn heralded by George Osborne has yet to rise
voicesJames Moore: As the Tories rub their hands together, the average voter will be asking why they're not getting a piece of the action
Dejan Lovren celebrates scoring for Southampton although the goal was later credited to Adam Lallana
newsComedy club forced to apologise as maggots eating a dead pigeon fall out of air-conditioning
Arts and Entertainment
Jo Brand says she's mellowed a lot
tvJo Brand says shows encourage people to laugh at the vulnerable
Life and Style
People may feel that they're procrastinating by watching TV in the evening
ebookA unique anthology of reporting and analysis of a crucial period of history
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
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

Senior Risk Manager - Banking - London - £650

£600 - £650 per day: Orgtel: Conduct Risk Liaison Manager - Banking - London -...

Commercial Litigation Associate

Highly Attractive Package: Austen Lloyd: CITY - COMMERCIAL LITIGATION - GLOBAL...

Systems Manager - Dynamics AX

£65000 - £75000 per annum + Benefits: Progressive Recruitment: The client is a...

Service Delivery Manager (Software Development, Testing)

£40000 - £45000 per annum: Ashdown Group: A well-established software house ba...

Day In a Page

Evan Davis: The BBC’s wolf in sheep’s clothing to take over at Newsnight

The BBC’s wolf in sheep’s clothing

What will Evan Davis be like on Newsnight?
Finding the names for America’s shame: What happens to the immigrants crossing the US-Mexico border without documents who never make it past the Arizona desert?

Finding the names for America’s shame

The immigrants crossing the US-Mexico border without documents who never make it past the Arizona desert
Inside a church for Born Again Christians: Speaking to God in a Manchester multiplex

Inside a church for Born Again Christians

As Britain's Anglican church struggles to establish its modern identity, one branch of Christianity is booming
Rihanna, Kim Kardashian and me: How Olivier Rousteing is revitalising the house of Balmain

Olivier Rousteing is revitalising the house of Balmain

Parisian couturier Pierre Balmain made his name dressing the mid-century jet set. Today, Olivier Rousteing – heir to the house Pierre built – is celebrating their 21st-century equivalents. The result? Nothing short of Balmania
Cancer, cardiac arrest, HIV and homelessness - and he's only 39

Incredible survival story of David Tovey

Tovey went from cooking for the Queen to rifling through bins for his supper. His is a startling story of endurance against the odds – and of a social safety net failing at every turn
Backhanders, bribery and abuses of power have soared in China as economy surges

Bribery and abuses of power soar in China

The bribery is fuelled by the surge in China's economy but the rules of corruption are subtle and unspoken, finds Evan Osnos, as he learns the dark arts from a master
Commonwealth Games 2014: Highland terriers stole the show at the opening ceremony

Highland terriers steal the show at opening ceremony

Gillian Orr explores why a dog loved by film stars and presidents is finally having its day
German art world rocked as artists use renowned fat sculpture to distil schnapps

Brewing the fat from artwork angers widow of sculptor

Part of Joseph Beuys' 1982 sculpture 'Fettecke' used to distil schnapps
BBC's The Secret History of Our Streets reveals a fascinating window into Britain's past

BBC takes viewers back down memory lane

The Secret History of Our Streets, which returns with three films looking at Scottish streets, is the inverse of Benefits Street - delivering warmth instead of cynicism
Joe, film review: Nicolas Cage delivers an astonishing performance in low budget drama

Nicolas Cage shines in low-budget drama Joe

Cage plays an ex-con in David Gordon Green's independent drama, which has been adapted from a novel by Larry Brown
How to make your own gourmet ice lollies, granitas, slushy cocktails and frozen yoghurt

Make your own ice lollies and frozen yoghurt

Think outside the cool box for this summer's tempting frozen treats
Ford Fiesta is UK's most popular car of all-time, with sales topping 4.1 million since 1976

Fiesta is UK's most popular car of all-time

Sales have topped 4.1 million since 1976. To celebrate this milestone, four Independent writers recall their Fiestas with pride
10 best reed diffusers

Heaven scent: 10 best reed diffusers

Keep your rooms smelling summery and fresh with one of these subtle but distinctive home fragrances that’ll last you months
Commonwealth Games 2014: Female boxers set to compete for first time

Female boxers set to compete at Commonwealth Games for first time

There’s no favourites and with no headguards anything could happen
Five things we’ve learned so far about Manchester United under Louis van Gaal

Five things we’ve learned so far about United under Van Gaal

It’s impossible to avoid the impression that the Dutch manager is playing to the gallery a little