# STEM Students answer Children’s Questions #5

### How do rockets get so much power to shoot into space?

-asked by Lea, 8, from West Jesmond Primary

Rockets are not too different from regular planes and cars – they all need something called ‘fuel’. The only difference is that rockets need a (lot of) special fuel to allow them to take off. The fuel is burned inside the bottom of the rocket which produces a hot gas (called an exhaust gas). This hot gas is pushed out the bottom of the rocket through something called a ‘nozzle’ (a tube that gets smaller closer to the exit) which makes the gas travel faster (acceleration). It’s this acceleration of the gas that’s used to push the rocket off the ground. Rocket fuel is special as it produces lots of energy compared to regular fuel – the same way some foods give us more energy than others (like chocolate!)
– Jenny, Mechanical Engineering Student

### Why are triangles the strongest shape to build lots of bridges?

-asked by Rosie, 10, from Ravenswood Primary School

Shapes that have straight sides are called ‘polygons’. Triangles are special because out of all the polygons, they have the least number of sides. Because triangles only have three straight sides, they are harder to squash than other shapes, for example: squares. If you look at the picture below, you can see how applying a force to a square would make it deform (squash), whereas no matter how you apply force to a triangle, this can’t happen because each side supports each other, which is why triangles are so strong! This is why engineers use triangles in their designs, to make their bridges as strong as possible.
-Jenny, Mechanical Engineering student

-asked by Emily, 7, from Simonside Primary School

When we refer to electricity, we mean the movement of tiny particles called electrons through a material that will allow them to pass through called a conducting material. An example of a conducting material is a copper wire which we usually see covered by rubber – if you have a charger for a tablet or phone then that is a great example.

To generate electricity, you usually need a fuel source. This could be in the form of coal or gas and nowadays hydropower and wind are becoming increasingly common sources of fuel. Electricity is generated through a machine called a generator which takes one form of energy and converts it into electrical energy. A common visual example would be a wind turbine. You can often find these in large empty fields or sometimes when you go to the beach you can see wind turbines far out in the ocean. Wind causes the blades of the turbine to spin which means magnets inside the wind turbine will also spin. These magnets are surrounded by copper wires which allow electrons to flow through them when the magnets spin around them and this flow of electrons is what generates electricity.
– Sidra, Mechanical Engineering Student

### How do TVs and computers work?

-asked by Yedam, 8, from West Jesmond Primary School

Computers and other electronic devices like TVs, phones and tablets all work in a similar way – they take instructions in the form of ‘code’ – code is just a language that computers can understand. These coded instructions are called ‘programming’. A computer scientist ‘programs’ a computer to work before we buy it so it can recognise our instructions – this is the computer’s ‘software’. When we give our computer an instruction (such as turning it on, clicking the mouse or going onto the internet) the ‘software’ tells the physical parts (the ‘hardware’) what to do.
– Jenny, Mechanical Engineering Student

As we have reached the end of the school year, here is a little round up of some of our favourite questions that children have asked us during STEM workshops.

### 1. Why doesn’t the energy ball give you an electric shock?

The energy ball is a little device we have that looks like a ping pong ball with two metal strips on top. Inside there is a light, a buzzer and a battery. If two people touch one metal strip each and then with their other hands touch each other, the ball lights up and buzzes. This works because we are conductors of electricity – electrons from the battery flow through us and back into the ball to complete the circuit.

The reason you don’t feel a shock when touching the energy ball because there isn’t enough electricity flowing through you to be able to feel it, and certainly not enough to harm you!

### 2. What do plants poo and wee? – St Wilfrids, Blyth

All living things have seven things in common – movement, respiration, sensitivity, growth, reproduction, excretion and nutrition. The sixth one, excretion, is a scientific word for producing waste. In humans, and many animals, that is our poo and our wee. They are the leftover waste products that our body doesn’t need so gets rid of.

Plants are living things, just like us, but you may have noticed they don’t poo or wee like we do. Rather than eat food like us, they make their own through photosynthesis. This produces a waste gas called oxygen which we breath in. Plants excrete oxygen rather than poo or wee.

### 3. Why does the moon control the sea? – Grange First School

Gravity is the force that keeps us close to the Earth, all really big things like planets and stars have a gravitational pull that attracts things near by. Because the moon is so big and so close to Earth it has quite a strong gravitational pull on our planet. The moon causes the water in the oceans facing it to pull towards it, resulting in a high tide. The pull of the sun’s gravity and the Earth’s own gravity also have an effect on the tides.

### 4. I’m the only one who can touch their nose with their tongue, is that because of my genes? – St Marys, Jarrow

Touching your nose with your tongue is known as Gorlin’s Sign. It is associated with a genetic disorder but not everyone that can do it has the disorder. About 10% of people without the disorder can touch their nose with their tongue and it does not appear to be due to genes you have inherited from your parents.

### 5. Why do we get goosebumps? – Billingham South Community School

We often get goosebumps when we’re cold, but they don’t do much to help us warm up, so why do we get them? Before we evolved to be modern humans, our ancestors were much hairier, we they got cold, getting goosebumps would cause their hairs to stand on end. As they had much more hair than us, they were able to trap a layer of air in the hair by doing this, providing them with extra insulation to keep them warm.

Although goosebumps are no longer helpful to us, we haven’t lost the trait through evolution because it doesn’t harm us. Therefore if a person was born with a mutation in their genes meaning they didn’t get goosebumps, they wouldn’t be at an advantage because of it so the non-goosebump genes wouldn’t necessarily be passed on more than the goosebump genes.