I'm pretty sure that what they work with is sodium acetate. What you've got is a super-saturated solution of sodium acetate, and as this begins to crystallise, it gives off a constant heat of about 55 degrees centigrade, which is a nice comfortable temperature for something like a hand warmer. Now how do you get this to work? Well as you bend the metal, I think you create surfaces that are like the crystals that could be formed from the solution. Once you've done this, you're really seeding the crystals, and so one forms and then another and another until it spreads throughout the bulk of the hand warmer. All the time it is giving off this heat. Eventually, the heat will stop because you've crystallised the whole thing. You can repeat the whole process by putting the used hand warmer in something like and oven, until the crystal is all melted again.

 

A sneeze is a bit like an itch in your nose. When you have an itch, it's extremely pleasurable to scratch it. Unless you have really long fingers, it's not that easy to scratch that far up your nose! So what sneezes do is use air to perform a metaphorical scratch. What we know about itching is that there is a special class of very small nerve fibres, and they signal itchiness. In fact, you can switch off the signals into the spinal cord and brain for itchiness if you cause a little bit of pain. That's why scratching an itch actually helps to relieve an itch, because you cause a little bit of pain and it switches off the itch signal. In sneezing, you get that pleasant relief because you've got rid of the itchy sensation, and also dislodged some of the gunge that's in your sinuses.

 

The reason that you get a rainbow, is that sunlight shines into a raindrop. Raindrops are very tiny and the surface of it is like a mirror. As the light waves go into a raindrop, they hit the mirror like surface and reflect. The light bounces off the back inside surface of the raindrop and comes back out of the front. Now if you've ever seen a prism, what that does is split white light into all the colours of the rainbow. White light is actually a mixture of lots of different colours. When the light comes back out of the front of the raindrop, it splits up into all the different colours of white light, and that's how you get a rainbow.

 

This is a Nobel Prize winning level of question, and if either of us could answer that, we'd probably be straight of to Scandinavia! The easy answer is, have you noticed that men tend to put weight on round their middle, and women tend to put it on round their bum? So there has to be a genetic component to this. The old saying goes that women have lots of fat around their hips and bums because that's their store for pregnancy. However, we don't know exactly why and how the body decides on the distribution of fat in the body. What we do know is that you can lose weight from those areas just as easily as you can anywhere else, if you resort to the right kind of exercise regimen. Energy in equals energy out, plus or minus any weight gain. So if you're not burning up the energy that you're putting into your body, the energy has to go somewhere. You body thinks that the most efficient way to store it is as fat, which it puts under the skin, or if, a man, as a bit of a beer belly.

 

It's luminol that you're activating. It's a chemical that things like glow worms produce. You can carry it around but to make it glow you need to activate it. What we usually use to activate it is hydrogen peroxide. When you snap a glow stick, it allows the two chemicals to mix together and causes a chemical reaction. The reaction won't last forever, but you can get to do what flies can do naturally.

 

 

 

It's True - Bed bugs can survive in your bed, feasting on you each night, for about 6 months.

It's True - the metal parts of boats are protected by a structure known as a sacrificial anode. This is a piece of metal, often zinc or magnesium, which is more reactive than the metal components on the boat (usually iron). So instead of the iron rusting, the sacrificial anode dissolves instead, protecting the boat.

It's True - superglue contains a substance called cyanoacrylate. Whenever it comes into contact with traces of water the cyanoacrylate molecules form a dense meshwork of crosslinks, gluing themselves together. That's why superglue sticks skin so well - because fingers are covered in a thin layer of sweat !

It's False - Fires won't burn properly without gravity. On earth heat rises carrying hot waste gases away from a fire and allowing fresh oxygen into the base to keep things burning. But in space, under microgravity conditions, there is no up or down so all of the waste gases from a fire accumulate around the thing that's burning, choking its air supply and putting it out.

It's False - The moon was caused by a planetary pile up involving the Earth and a second Mars-sized planet, notionally named Theia, which occurred not long after the Earth first formed. The resulting collision threw huge amounts of Earth's crust into orbit where it slowly aggregated to form the moon.

It's False - It's a fallacy that all fish are cold blooded. Some sharks, including salmon sharks, are warm blooded and have a core body temperature similar to our own. They produce this heat by continuously swimming, burning off energy in so-called red muscle deep inside their bodies.

It's False - in the eye of a hurricane, which ranges from 8-200 km across and lies at the centre of the storm, it is calm and still, fooling some people that the storm has passed. In fact the other half is still to come. The fastest wind speeds tend to be recorded at the edges of the eye.

It's True - During their short lifespans the average bee clocks up at least 500 million beats of its wings.

It's False - the average human moves their backbone at least 100 million times during their life.

It's True - The build up of pressure inside your nose brings the hum to a halt after a second or so !

It's False - 3 is the square root of nine. The cube root is 2.08008382.

It's True - they hop along at 40 miles per hour.