Let’s hear it for the little people! Two schoolgirls took on the might of GlaxoSmithKline when their science project revealed that the New Zealand brand of Ribena contained no trace of vitamin C at all. Whoops! So much for the “four times more vitamin C than oranges” claim and now £80,000 poorer too. Of course that would never happen in the UK.  Oh no.  Just goes to show you though, what you learn in science at school can come in very handy. Spread the word.

The line-up this week:

1. Pedant’s Corner: Weight for it…
2. RS books
3. Activity of the Week: Solar Still
4. Mouses at the Ready for Flipside magazines
5. Noticeboard: FYI
6. Recommended websites of the week
7. The Winners’ Enclosure
8. Joke of the Week

Here’s Ian Francis to put us on the straight and narrow, science-wise. Over to you Ian!

			More pedantry, and this time it’s heavyweight. Or do I mean ‘massive’? This week, I’m talking mass and weight. People tend to use ‘weight’ to mean both, but to scientists they are two different, (although related) quantities. Mass is a measure of how much matter (‘stuff’) there is inside something, basically boiling down to the kind of atoms inside, and how numerous they are.  It’s measured in kilograms (see Ben’s excellent piece from last week’s newsletter). Weight is a measure of the force with which gravity attracts said mass. Being a force, it should be measured in newtons, (no matter what the ‘weighing’ scales at Tesco’s say). The two are related by multiplying mass in kg by the force with which gravity acts on each kilogram. On Earth, gravity acts with a force of about 10 newtons per kg, so a 2kg sack of spuds has a weight of 20N, and an 81kg Planet Science newsletter contributor weighs in at 810N. I reckon the reason we ‘mix and match’ mass and weight is because we never really deal with situations where the gravity acting on a mass is anything other than 10N per kg. Most of us won’t experience freefall in an orbiting space ship, where you’ll have zero weight, but the same mass as ever. Neither are we in the habit of taking holidays on the moon, where everything weighs less, but still has the same mass as back home. So, the next time you ride a lift quoting a maximum permissible ‘weight’ in kg, feel free to raise an eyebrow quizzically. And if you overdo the Easter eggs next month, why not join me at ‘Masswatchers’ to lose that extra kg or three?

Ready?

Tadaaaaa! The Junior Shortlist can be revealed….

Whether you’re in one of our Planet Science junior judging panels or not the shortlist is looking pretty interesting we think you’ll agree.

Can You Feel the Force? by Richard Hammond

How Nearly Everything Was Invented By The Brainwaves, by Lisa Swerling and Ralph Lazar

It's True! Space Turns You Into Spaghetti by Heather Catchpole and Vanessa Woods,

KFK Natural Disasters by Andrew Langley

My Body Book by Mick Manning and Brita Granström

Science Investigations - Electricity by John Farndon

To find out more about these six and to get the ISBN numbers in case you feel a trip to the book shop coming on visit the Royal Society’s own page.

Inspired by our 'April Aquifer' quiz about water, (see notice board below) Activity of the Week is here to save your life.

Picture the scene – you’re laid out on a raft, the sun is beating down, your mouth feels like the bottom of a birdcage.  “Water! Water!” you gasp through parched lips.  The seawater surrounding you mocks back “Hah! Try drinking this matey and you’ll know about it!”

But wait! What’s this?  You managed to grab a large bowl, clingfilm, sticky tape, a glass and a small rock before the ship sank (!).  Thank goodness for that! Now all you need is to make a solar still…

You will need:

• large bowl
• short glass or cup
• plastic wrap
• small rock
• pitcher of water
• salt
• long spoon for stirring

What to do:

1. First make saltwater by adding salt to fresh water. Stir the water until the salt dissolves.
2. Now pour about two inches of saltwater in a large bowl.
3. Take an empty glass and put it in the bowl. The top of the glass should be shorter than the top of the bowl, but higher than the saltwater.
4. Put clingfilm over the top of the bowl. You may need to use tape to make sure the seal is tight.
5. The last step is to put something heavy right in the centre of the clingfilm, over the empty glass. That will weigh the plastic down and help you collect the water. Now you've made a solar still. It's called a still because it distills, or purifies, water.
6. Leave your still outside in the sun. Leave it alone for a few hours, or even a whole day. The longer you leave it out, the more water you'll collect.
7. When you're ready to check your still, take the plastic wrap off and look at the water that's collected in the cup. Do you think it's salty or fresh? Taste it – it’s fresh!

What’s going on?

Rays from the sun heat up the salty water in the bowl. When the water gets warm, it evaporates and becomes a gas. When the gas rises and hits the clingfilm, it turns back into water droplets. Eventually, gravity makes the water droplets roll down the clingfilm towards the rock. Then the water droplets slide off the clingfilm into the glass. The salt doesn't evaporate, so it gets left behind in the bowl. Water evaporates in the same way from lakes, rivers, and oceans. The water heats up, turns into a gas, and then condenses to fall back down as rain.

Now, can you distill fresh water from other liquids like cola or orange juice?

Did you know?

This can also be done with urine if you're in the desert and water is hard to come by. If you do not have a pot, you can just dig a hole in the ground, do your business in the hole, place a glass/container in the middle and cover with something (plastic bag works). The natural heat of the sand will evaporate the clean water into the glass. Needs must, eh?

This week we’ve got ten March Flipside magazines to give away. Ten strangest sports from underwater hockey to mountain uni-hockey. Thermograms – pictures that visualise temperature and much more.

For more details see the flipside site.

If you want to win one, send an email with your name and address, and the words FLIP IT in the subject line, to planet-science.news@nesta.org.uk.

The draw will take place at 5pm on Wednesday 4^th April.