## [WATCH] How do planes stay up in the air?

This great question was sent in by six year old Cathal, who can sometimes be found over at Bumbles of Rice blog; Cathal has a really scientific mind and is always asking him mum lots of questions. Sometimes she sends them on to me, which I really love.

I thought that Cathal’s question was a great excuse to try out another whiteboard video, I hope you like it Cathal and keep those questions coming!

## How do planes stay up in the air when they are so heavy?

It is a common question and one that we all want to know; especially if we are sitting on a plane about to take off! So if you want to know how planes stay up in the air, make sure you watch this video below to find out!

Planes are pretty big machines; the world’s largest passenger plane is the Airbus A380 which can weigh as much as 560,000 Kg.

That is a lot of plane to get into the air and keep it there.

`The largest passenger planes is the Airbus A380, weighing in at a massive 560,000 kg`

Even smaller planes, with all their equipment and passengers and baggage, are pretty heavy things, so how do they stay in the air?

We think of air as being very light as we move through it all the time. But remember air is made up of tiny molecules that can actually be really strong too, there are lots of them and they can move together with quite a force.

Air can be so strong it can blow over people, cars and even buildings when it moves very fast, like a tornado!

It can be strong enough to hold a plane in the sky too, but we don’t need to create extreme weather conditions to do so, we just need to consider four important forces, and get them just right.

The four forces are LIFT, GRAVITY, THRUST and DRAG!

These four forces act in different directions… Lift pushes the plane up, Gravity pulls it down, Thrust propels it forwards and drag pushes it back.

`The four main forces acting on a plane in flight are lift, gravity, thrust and drag`

If we can get these four forces balanced just right, we can get a plane in the air, and keep it there.

## Lift

Let’s consider LIFT first, and to do that we need to look at the shape of the plane, and in particular… the wing. We call the wing shape an aerofoil, it is curved at the top, like this. This shape is designed to make air move faster over the top of the wing than below it.

When air speeds up its pressure decreases (this is in keeping with a law of physics known as the Bernoulli’s principle).

Bernoulli’s principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure

When the air pressure on top of the wing is less than the air pressure below the wing it creates a force called LIFT which pushes upwards on the wing.

## Gravity

GRAVITY is the force that pulls the plane towards Earth; it keeps it on the ground. In order for the plane to get into the air, the LIFT force needs to be greater than the force of GRAVITY.

To get enough air moving over the wings of the plane it need to be travelling through the air at quite a speed.

## Thrust

We use engines to propel the plane forward using a force called THRUST! The more thrust is generated, the faster the plane goes and the more air travels around the wings. LIFT increases until its force is greater than that of GRAVITY and the plane takes off into the air.

So far we have covered three of the four forces… LIFT, GRAVITY and THRUST. There is one more to consider… DRAG.

## Drag

DRAG can be described as a force that acts against a moving object. So, in this case, the plane is being propelled through the air, by the force of THRUST, but that air is moving against it, and creating a DRAG force.

THRUST moves the plane forwards, DRAG pushes it backwards. In order to keeps the plane moving in the right direction, THRUST must be greater than DRAG. Planes are designed to be streamlined – to allow air pass around them with the least amount of resistance – to reduce DRAG.

## A bit of Balance

So a plane can stay in the air once the four forces… Lift (up), Gravity (down), Thrust (forward) and drag (backwards) are kept at the right balance.

Essentially the plane needs to have no net force acting on it, which means that each of the forces balance each other out.

## Newton’s Law of Motion

Let’s consider one more law … Newton’s Law of Motion which states that an object at rest will stay at rest and an object in motion will stay in motion, once there is no net force acting on it.

Newton’s first Law of Motion which states that an object at rest will stay at rest and an object in motion will stay in motion, once there is no net force acting on it

What this really means is that, once all these four forces are balanced, the moving plane, will stay moving… in the air… in flight!

Which is just the way we like it!

A big thanks to Cathal for sending in this question; if you have a question you would like me to answer just leave it in the comments below or sent it to me by email.

## Mystery Creature – April 2017

Hard to believe that it is time for another Mystery Creature, the months are flying by. This one looks like some kind of mini alien.

`Image credit: Jymm; Image source: Wiki commons`

### A couple of clues?

In keeping with the alien theme, they have been known to host their own invasions – baffling people as they suddenly turn up, en-masse, on seashores.

They are not much bigger than the top of your finger, but does that make them harmless?

### Over to you

Friend or Foe, what do you think? Do you know what it is?

As always, feel free to leave comments; make predictions, maybe get your whole family or classroom in on the act. I will happily reply to any comments and I will post a full reveal about this creature at the end of the month.

## Mystery Creature revealed – the Flannel Moth Caterpillar

It is hard to believe that March is over already and that it is time to reveal this month’s mystery creature already. Here is a little reminder…

Did you guess it? It is the…

Flannel Moth Caterpillar (Megalopyge opercularis), often referred to as the Trumpapillar, for, ahem, some very obvious reasons 😉

Here is another image, in case you need more convincing on the Donald Trump connection.

`Photo credit: Andreas Kay`

They are found in a range of colours, mainly yellows, greys and browns.

These cute and fluffy looking caterpillars are a lot more harmful that they appear. Those silky looking hairs that cover the body contain tiny spines capable of injecting toxins into any victim that come into the slightest contact with them. They say it is an experience you will not forget in a hurry. The immediate symptom is searing pain at the area of injection, where a number of dark red spots usually appear. Most victims don’t get away with just that though; other symptoms include headache, nausea or vomiting, abdominal cramps, chest pains and, for some, serious respiratory distress or shock like symptoms. Although medical attention is needed in such cases there is no antidote to the toxin, the symptoms usually abate with time; the pain usually lasts for at least 12 hours.

## A bit of mimicry

These caterpillars are so good at being bad that other try to mimic them, for their own safety, take a look at the video below for more on this amazing caterpillar and those that try to look just like it.

Luckily, the venomous phase of this creatures life cycle is limited to its caterpillar state. The adults pose no threat at all and look like this…

`Image credit: Patrick Coin`

## How common are the moths and where can they be found (or avoided)?

The inch long caterpillar is fond of feeding on many garden plants and common trees such as oak and elm. It can be found in many regions of the United States (primarily eastern and southern states), Mexico and parts of Central America. There are often two breeding species per year, making early Spring and early Autumn the most likely times to get stung.

Have you ever come across a venomous creature? Or maybe one that reminds you of someone you know? If so, please let us and share your story in the comments below.

Remember to check back for another mystery creature next week!

## Netflix stream team – our current family viewing

We have had some dark weather and lots of rain recently so Netflix has been appreciated all the more in this house. Last week we received a lovely gift from Netflix, some cozy slippers, a nice relaxing herbal tea, a lovely lavender and chamomile spray and a mini beanie for the tablet.

The children were quick in coming up with ways to use everything (I got the tea, they made off with everything else). They asked could they all pop into our bed that evening and watch Netflix on my ipad using the new beanie. As it was the start of the long weekend I decided to give it a go (figuring they’d last five minutes before I’d have to break it up). I settled them in and even sprayed the lavender and chamomile on their pillow and headed back up to the fire and my book. To my amazement their idea worked. They snuggled in and watched the whole moving without any arguments and afterwards they all fell off to sleep really quickly.

Thank you Netflix!

## What are the children watching?

### Penelope

What were they watching that night? They watched Penelope, a real feel good movie and all three kids gave it the thumbs up!

A modern romantic tale about a young aristocratic heiress born under a curse that can only be broken when she finds true love with “one who will love her faithfully.

### Lemony Snicket’s A Series of Unfortunate Event

The children are also enjoying the Netflix original series of Lemony Snicket’s A Series of Unfortunate Event. They are big fans of the original movie which is also available on Netlfix. So far they are really enjoying this eight episode series; they seem to think it is a little darker than the movie with a lot more details and plot lines.

### Two by Two

The youngest got to choose a movie for another recent movie night and he chose Two-by-two. I watched it with the kids too and it is a really sweet movie, about fitting in, finding friends and realising who you really are (or if you don’t want to psychoanalyse it, it’s just a cute animated movie!).

### Middle School – the worst years of my life

At Hills Village Middle School, budding cartoonist Rafe and best pal Leo challenge their uptight principal by breaking every rule in his handbook.

My kids loved this movie and it prompted my middle child to start reading the books, which is a win-win, right?

## What are the adults watching?

### Grace and Frankie

I can’t wait to get stuck into the third season of Frankie and Grace, which will be released in just one more day (the 24th March to be exact). I really enjoyed the first series and was a full blown fan by the end of the second season so I really can’t wait to see what the lovely pair get up to in this next season.

Here is a trailer for the new series:

### I don’t feel at home in this world anymore

We really enjoyed this new Netflix movie starring Elijah Wood and Australian actress Melanie Lynskey – I don’t feel at home in this world anymore. If you like quirky movies then check this one out.

### Grimm

We have started watching Grimm, a series about a cop who suddenly inherits some special powers and realises that not all people are what they appear. It is early days but we are really enjoying the first series so far.

### Iron Fist

This is brand new to Netflix this month and we have watched the first two episodes so far. It was a little slow to start but has good promise and we are all Marvel fans in this family (although the movie is rated 18s).

Danny Rand resurfaces 15 years after being presumed dead. Now, with the power of the Iron Fist, he seeks to reclaim his past and fulfil his destiny.

What are you watching on Netflix at the moment? If you have any current favourites let me know in the comments below.

Disclosure: As a member of the Netflix Stream Team I have received a years subscription to Netflix, free of charge, and an Apple TV, for streaming purposes. As part of Netflix Stream Team I will be posting monthly updates on what we are watching and what is on offer.  All opinions expressed will be my own.

## Why does my tummy rumble?

I’m back with another great question this week, send in by Sarah, who wants to know …

Why does my tummy rumble?

It is all explained in this short video, just click to play (or, if you prefer, you can read the answer below).

While we sometimes find the noise a little embarrassing it is actually a really natural, and essential thing and shows that our bodies are working correctly, but why all the noise?

Let’s take a closer look!

The noises come from our digestive system, which is basically a long tube that stretches from out mouth to our anus! It usually comes from our stomach or small intestine.

The wall of this tube is mainly made up of muscles, called smooth muscles, which move in a certain way to push food through the system. This muscular movement is called peristalsis and this is how it works…

A small area of muscles contract, a bit like squeezing a ring around a part of the tube and this pushes things like foods, liquids and gases forward a little; then these muscles relax and the muscles in front of them contract and so on, pushing food and other content down the tube with each contraction.

Think about squeezing toothpaste from a tube!

The noises we hear are due to the movement of food, liquids and gases down the digestive tract. We associate the noise with an empty stomach, or being hungry, but the sounds are made when we have food in our system too. We often don’t notice them as the sound is dulled down.

When our digestive system is empty the noise is a lot louder.

It makes sense that peristalsis happens when we need to pass food through our digestive system, but why all the activity when our stomach is empty? Well this is the result of something called the Migrating Motor Complex or MMC for short!

This usually happens when our stomach and intestine have been empty for about two hours; a type of electrical pulse is triggered and this causes peristalsis through the digestive system. This serves a type of cleansing function; it clears any pockets of leftover food, mucus, bacteria and other debris from the stomach and small intestine.

`The MMC response is usually triggered when our digestive system has been empty for about 2 hours`

The MMC response is triggered every 90 to 120 minutes, until the next meal is eaten. It does tend to quieten down a bit while we sleep and then ramp up the activity again when we waken, which is why we often have gurgling tummies in the morning.

I hope you enjoyed this short explanation and video; Do let me know in the comments below and as always, if you have a question you’d like answered just leave it in the comments below!

## How to make rainbow silly putty

People are always asking me for a slime recipe that doesn’t require borax powder. This is one option, making silly putty. We love this recipe, using just cornflour and washing up liquid (or you can use liquid soap instead); just be careful that you use products that you know won’t irritate your child’s skin.

We thought we’d share this one, in honour of St. Patrick’s Day…. with all the shamrocks and the leprechauns and the rainbows 😉

### You will need:

• Cornflour
• Liquid soap or washing up liquid
• A bowl
• A spoon
• Food colouring

### What to do:

Just click the arrow button on the right of the image below to find out how to make this brilliant rainbow silly putty; it is so easy and my kids loved it!

### The results:

We mixed all our silly putty together for the rainbow effect but you can keep the colours separate if you prefer. This silly putty is great to play with, mold it in your hand, stretch it, fold it… it makes a great stress busting tool too! It will last for a week or more if you put it in an airtight container or plastic bag but we usually just make a new batch each time.

Let me know if you try this yourself! We have had lots of fun working on other slime recipes and will be sharing them soon so remember to check back or follow the blog to make sure you don’t miss any posts!

## Are all raindrops the same size?

As you know, I love receiving your questions and I am always thinking of different ways to answer them. Some you will find in my regular column in the Irish Examiner, some I answer here on the blog, in written, video and info-graphic form.

Here is something a little bit different and I am hoping to make it a regular thing, so please let me know what you think and keep those questions coming!

### Are all raindrops the same size?

In order to answer this question we need to first understand how raindrops are formed. And that story starts right down here on Earth. We have lots of water in the form of rivers, lakes and seas and when this water heats up it changes into a gas, called water vapour which rises up into the air.

The sky actually has lots of bits floating around in it – like dust and smoke particles. The water vapour tends to form tiny droplets of water around these little specks of dust and smoke and these droplets come together to make clouds.

At this stage the tiny drops are light enough to stay in the sky, but, as the cloud fills up with more and more of them they tend to start to bumping off each other and as they do they join together to form bigger droplets. Eventually they get so big and heavy that they can no longer stay in the cloud and they drop down towards the Earth as rain.

A water droplet needs to be at least ½ mm in diameter before it will fall as a raindrop.

Depending on how many droplets have joined together to make that raindrop, we already have drops of different sizes falling from the clouds.

What shape doe you think the raindrops are? Teardrop shaped maybe? No, not at all! Although raindrops are usually depicted in this teardrop shape they actually start off as nice round spheres. They have lots of forces acting on them, like surface tension which acts on the surface of the drop keeping it in that nice round shape.

As the rain drops fall they experience other forces too like air pressure. As it pushes from below and above the rain drops get squished into sausage like shapes until they eventually split into a number of small drops of various sizes and these are what fall to the ground.

So, are all raindrops the same size? Definitely not!

And they are not all teardrop shaped either.

****

A big thanks to Ewan for sending in this question. Remember to keep sending in your questions. You can leave them in the comments below.

I’d love to know what you think of this video, there are lots of improvements I want to make and I’d love your comments and feedback.

## Mystery Creature March 2017

This month’s Mystery Creature is a pretty hairy fellow. Can you name him?

`Image source: (Jeff Delonge) Wikimedia Commons.`

As always, if you are not sure, feel free to ask questions! I’ll post the big reveal at the end of the month.

## The perfect pancake formula

We are big fans of pancakes in this house; I’m pretty casual with my batter making at this stage, I throw a few things into a bowl or blender, a bit of a mix, into the pan, quick flip and hey presto! It seems I am going about it all the wrong way. There are formulas that I should be following, such as…

1. ## The batter formula

If you take your pancakes seriously, you’ll want the appearance to be just right. It’s not just luck or habit; it is all about the flour to liquid ratio, according to a group of researchers at University College London.

The thickness of the pancake determines the way the water in the pancake is released during cooking and ultimately determines the overall appearance of the finished product.

The experts devised a formula…

Mixture (ml) required per pancake : (D² x T x π) / 4

Total mixture (ml) required: (D² x T x π) / 4

… where D is the diameter of the pancake pan and T is the thickness that you want your pancakes!

And believe it or not, this pancake study has medical benefits too: the team are using what they learned to create better surgical methods for treating glaucoma, which is a build-up of pressure in the eyes caused by fluid.

1. ## The perfect batter calculator

If this all sounds a bit too complicated then don’t worry, maths students at the University of Sheffield have taken this formula and generated a calculator that does all the maths for you. All you need to do it type in how many pancakes you want, how thick you want them and how wide your pan is and voila, you get an exact recipe!

1. ## The super formula

If you like your pancakes with some extra maths then don’t worry, there is a formula for you too, but hold on to your whisks, this one is pretty tricky!

100 – [10L – 7F + C(k – C) + T(m – T)]/(S – E)

Apparently, the closer you get to 100, the better the pancake.

L is the number of lumps in the batter; C is that consistency.

F stands for the flipping score, k is the ideal consistency of the batter and T is the temperature of the pan.

M is the ideal temp of pan is, S is the length of time the batter stands before cooking and E is the length of time the cooked pancake sits before eating.

Are you still with me? If not don’t worry. If everyone in your house is happy to eat your usual offerings then I’d go back to the old reliable. Me? I’m taking my inspiration from this post and I’m going to add some colour and sprinkles… without a calculator in site.

Whatever way you make your pancakes today, I hope you enjoy 🙂

*******

If you want to know a little more about your pancakes, from history, to ingredients, to science, check out my post over on Headstuff.org today!

## Mystery Creature revealed – the Silkhenge spider

How did you do with this week’s mystery creature (or more accurately… mystery structure). A few of you got it spot on, well done.

`Image credit:Phil Torres (with permission)`

This stunning piece of architecture was built by…

The Silkhenge spider!

This tiny structure is made up of two parts, a central spire on the inside and an outer (round) fence like structure,  a little more than 0.5 cm in diameter. The entire structure is made of silk and there are threads attaching both the inner column and the outer ring.

This structure is amazing for so many reasons;

Firstly, it was only discovered as recently as 2013, by Troy Alexander, in the Tambopota Research Centre in the South Eastern Peruvian Amazon. Originally there was much speculation as to whether a spider was actually the creator at all. Some suggested it was the work of a caterpillar, others thought it was a fungal structure of some sort.

Secondly, no spider has ever actually been seen creating these structures! Researchers did finally observe small spiderlings that had hatched from the central structure. Usually there is just one solo spiderling , occasionally there are two. This is extremely rare for spiders, as you are much more likely to find tens, or even hundreds of eggs within the one egg sac. It is possible that the female spider that makes these structures, makes many, maybe there are better chances if survival of the eggs are dispersed over a wider area. A literal case of not putting all your eggs in one basket?

Check out this fantastic video by Phil Torres and Aaron Pomerantz as they capture the moment two spiderlings hatch (it really captures an exciting moment in the discovery process)…

`Video Credit:Phil Torres`

Thirdly, scientists are still unsure what purpose the structures serve. Do they have a protective role: a fence to keep out predators? Or do they act like a typical web, trapping insects and filling the nursery larder with a food supply for the hungry hatchling?

Finally, the most bizarre part of this story is that the adult spider, the skilled architect behind these constructions, is still unknown. As mentioned in the video above, DNA barcoding has not yielded any positive results. No doubt the answer will come soon, but in the meantime, it is still a case of speculation and wonder, often a very fun part of scientific research 🙂

I’ll be posting March’s mystery creature next Monday so remember to stop by!