Why is the sky blue? Part 2

Where are all the dinosaurs, what are people made of, and why can't we fly? We arm parents with 25 answers to children's tricky science questions.

26) How do planes fly?

Their wings have to be, well, wing-shaped! The typical wing has a flat bottom and curved top. When air passes over the wing it takes longer to cross the top than the bottom, so the air has to travel faster over the wing. When air speeds up its pressure falls, so the wing naturally wants to rise into the area of least pressure, which gives the plane ‘lift’.

27) Why aren’t birds electrocuted while sitting on electric wires?

Because they’re only touching one wire. For electricity to flow there needs to be a difference in voltages between two points. If the bird touched two wires, or one wire and the pole, a current would flow through the bird.

28) Why is water wet?

The feeling of ‘wetness’ is actually a feeling of coldness. Because of the electrical properties of water it likes to stick to objects so when you get wet it clings to your skin. Your warm skin then begins to cause the water to evaporate, cooling the area and your brain interprets the sensation as ‘wet’.

29) How do sunglasses work?

Cheap sunglasses, or non-polarised ones, simply block the amount of light reaching your eyes by using darkened lens. Polarised sunglasses, or expensive ones, do this too but also prevent glare. Glare occurs when sunlight bounces off water, metal, etc. Reflected light is usually horizontal and the polarised lenses only allow vertical light to pass through.

30) How do flowers grow?

Flowers need the sun, water, nutrients... and bees! Their leaves soak up the sun’s rays and turn them into food, while their roots suck up water and good stuff from the soil. Bees, meanwhile, allow plants to reproduce by spreading pollen.

31) Where do bogeys come from?

Your nose acts like a filter for the air that you draw in through your nostrils. To catch any unwanted debris such as dust, smoke and germs, your nose constantly makes mucus. When the mucus holds too much debris it dries out and can clog up your nose.

32) Where do bees go in the winter?

Honeybees gather round the queen in their hive to stay warm and live off the honey they made during the summer. Male bumblebees die out and are replaced in spring when the queen has bee babies.

33) What is the fastest animal?

The fastest animal on land is the cheetah, which can reach speeds of 110km/h, which is also the same top speed of the fastest animal in the sea — the sailfish. Both are left standing by the fastest animal in the sky, the peregrine falcon, which can dive on its prey at 390km/h.

34) How do microwave ovens work?

Microwaves cause the water molecules in food to vibrate, which causes heat. Water absorbs the microwaves but metal and plastic do not, which explains why you can hold the container of piping hot food. Contrary to belief, the food is not cooked from the inside out, but evenly throughout.

35) Why are there no dinosaurs alive today?

About 65 million years ago an asteroid hit the Earth in modern-day Mexico, causing massive fires, sending huge clouds of dust into the atmosphere and cooling the planet. Anything bigger than a cat died out. However, birds survived and they are directly related to dinosaurs.

36) What weight is the Earth?

The mass of our planet is 5,970,000,000,000,000,000,000,000 kilogrammes, which is roughly 6,000 billion billion tons or 6 sextillion tons. Or 30 billion billion blue whales!

37) What is air made of?

We don’t need most of the air we breathe. It is made up of 78% nitrogen, 21% oxygen and 1% carbon dioxide and nobel gases. So, 21% of each breath

we take in is made of the gas we need to survive, but each breath we breathe out holds about 14% oxygen.

38) Why are there different times on Earth?

Otherwise it could be noon in the middle of the night or 10pm at dawn! People across the world have always marked time according to their location, each calling 12pm or noon when the sun was highest in the sky. Time zones were introduced once people began communicating and travelling across vast distances,to make things simpler.

39) Where is the warmest place in the world?

The record for the hottest place ever recorded goes to the city of El Azizia, in Libya. On September 13, 1922, thermometers there reached 57.8C — about 24C warmer than Ireland’s record.

40) Why is it cold in the winter?

When the Earth spins in space it doesn’t act like a spinning top in full flight. It has a slight wobble, like a spinning top that’s just about to fall over. This makes the planet ‘nod’ at the sun, so the sun gets to shine directly on the northern hemisphere (where we live) in the summer, then sinks lower in the sky in the winter, which is why it gets colder.

41) What are people made of?

Mostly water. By weight, our bodies are mainly made of 65% oxygen, 18% carbon, 10% hydrogen, 3% nitrogen, 1.5% calcium, and 1% phosphorus.

42) How does a magnet work?

A magnet’s atoms all point the same way, north-south, and create a magnetic field. In a piece of normal metal the atoms point in different directions. When the magnet draws near these atoms begin to align themselves, pointing along the magnetic field and attracting the other atoms in the magnet.

43) If I swallow chewing gum will it stay inside me for years?

No foodstuffs we eat stays inside us for years. What makes gum ‘chewy’ also makes it hard for saliva to dissolve. Stomach acid also finds it difficult to break down, but within 24 hours of swallowing it the gum will eventually come to the end of the digestive process.

44) Why can’t humans fly?

Gravity is too strong and we’re too big. To overcome the Earth’s pull we would have to burn a lot of energy to take to the air. Our heavy bodies and solid bones and the fact that we don’t have wings mean we must rely on machines to get off the ground.

45) How do batteries work?

Pop some AA batteries into a flashlight and electricity from them powers the light. There are different substances in a battery which react once the terminals (+ and -) are connected. Basically, one substance creates electrons, another absorbs them and a current flows out to power the light.

46) What is a shooting star?

They are meteors, usually no bigger than grains of sand that enter Earth’s atmosphere at such high speeds that they burn up as they fall. They are leftover material from the early solar system or bits of dead comets. Sometimes, this material is much larger and can burn brightly (called a fireball) and reach the ground (called a meteorite).

47) Why are my eyes a different colour to others’ in my family?

Each child gets two copies of each gene. For eye colour, the child is more likely to inherit the dominant gene, which is usually brown. If mum or dad has brown eyes, then their children will most likely have brown eyes. However, there are more than just eye colour genes at play and it is possible to have one blue-eyed child in a family of brown eyes.

48) What is the most powerful computer in the world?

Supercomputers are calculators the size of rooms, which scientists use to for problems such as weather predictions and code breaking. The most powerful supercomputer today is the Fujitsu K computer, which can perform one million billion separate calculations per second.

49) How far away is space?

If you could drive to space by car you would be there in less than an hour. There is no ‘Welcome to Space’ sign at the border but it is generally accepted that space begins about 100km above our heads.

50) How many stars can you see with the naked eye?

It depends on how dark the sky is. If you are near street lights and urban areas you will struggle to pick out more than a couple of dozen. However, if you can get out into the countryside you will be rewarded with the sight of up to 2,000 stars.

The first 25 questions can be viewed here.