The Leaning Tower of Pisa - Galileo's Experiment

I went on holiday to Italy not long ago and whilst I was there, I visited the Leaning Tower of Pisa. This is the place of Galileo’s experiment where he dropped two cannonballs of different masses to see  whether they would hit the ground at the same time. They did. 

Many people would argue that they wouldn’t (if they didn’t know the outcome of the experiment already). This is understandable as common sense tells you that heavier objects have a larger force of attraction and will therefore accelerate towards the Earth faster than lighter ones. However, acceleration is not just derived from force, it also depends on mass (a = F/m, acceleration = force / mass, Newton’s Second Law of Motion). 

Let’s substitute some figures into a = F/m. Take a 1kg chinchilla and 100kg panda. If we were to only think about the force acting on these animals (ignoring air resistance), the panda would hit the ground first. This is because 100kg, the panda’s mass, results in 1000N of downward force (due to the Earth’s gravitational field strength of around 10N/kg). The chinchilla’s downward force would only be 10N. Now let’s put the effect of the animals’ masses into a = F/m.

acceleration = (1000 N / 100 kg) = 10 m/s/s

acceleration = (10 N / 1 kg) = 10 m/s/s

The acceleration is the same regardless of the force. The panda's mass gives it more inertia (this is an object's resistance to changes in its current state of motion), this means it is more difficult to get the panda moving compared to the chinchilla. The panda's mass has an inverse effect on its acceleration and therefore causes the two animals to accelerate at the same rate.

The Physics of Flight

I recently went on holiday to Italy, this required me to fly which got me wondering: How does an aeroplane fly whilst carrying so much weight? I went on a little journey of discovery and found out.

Takeoff

During takeoff, the plane's engines produce a great deal of force (thrust) pointing in the opposite direction of the plane's travel. According to Newton's third law of motion, this makes the plane move forwards (every action has an equal and opposite reaction). Due the movement forward, air is rushing over the plane's wings. The carefully designed shape of the wings forces this air downwards which causes an upward force called lift. This lift is what causes the plane to go upwards and the thrust from the engines is what causes it to move forwards.

Flight

The plane is now suspended in the air. It doesn't fall to ground because the lift produced by the air rushing downwards exactly balances the weight acting downwards. The plane keeps moving forwards because the thrust from the engines is greater than the air resistance.

There you have it, flight in its simplest terms.

The Day I met Professor Brian Cox!!

25/6/15

Today, I met Professor Brian Cox. My head of year leader told me that he was coming to congratulate a group of students at my school for completing a course and decided to let me see him as well as she knew how much I loved physics.

I left my ICT class early to see Brian and on the way knocked on my maths teacher's door, she came with me too as she also likes physics. We made our way into the hall and saw him stood not too far away. One of the teachers who helped to organise the event took me up to the professor and introduced me to him. I was extremely nervous talking to him as he is someone I look up to and we talked about how much I like physics and whether it is something I would consider as a university course option (which I definitely am!) and I got him to sign my book (Why does E=mc²) which was also signed by the other author, Professor Forshaw.

After meeting him, he went away to see the other people. My maths teacher was also dying to see him so another teacher brought him over to where we were standing and he talked to her. I grabbed this opportunity to ask him about nuclear fusion. My question was about tokamaks and how they work. He said that for nuclear fusion to happen, the atoms have to be ionised (stripped of electrons) this means that the net charge of the nuclei is positive (as there will only be protons (positive) and neutrons (neutral) left). The method used with tokamaks is magnetic confinement, this means that they use magnetic fields to contain the positive nuclei whilst they 'whizz' around within, occasionally bumping into other nuclei and starting a nuclear reaction.

It was a pleasure meeting Professor Cox and I hope to see him sometime in the future.

St Peter's School: Physics Olympics

17/6/15

Today, I went to St Peter's School to take part in a physics competition! Our team comprised of two girls and two boys, all of us are physics geeks. We had a great time meeting like-minded people and having a go at the challenges during the day.

The first challenge we took part in was called 'Payload'. Teams had to design a boat with basic materials like card, a sheet of acetate, plastic bottles etc. and then we had to see how many marbles they would hold. Our boat managed to hold 69 marbles before it sank.

The next challenge was called 'Good Vibrations', in this one, we had to determine the weight of a toy duck using an oscillating ruler and some weights. First we timed how long it took a 50g weight to oscillate 20 times, next we timed a 100g weight and then 150g. We plotted our results on a graph. We then measured how long it took the duck to oscillate 20 times and, using the line of best fit, we found out its weight.

Next, we had to create an electromagnet and see how many paperclips we could pick up. We had a choice of whether to use a core of aluminium, steel, or iron. We were also able to choose how we connected our circuit. The best way to pick up the most paperclips was using a core of either steel or iron and connecting two cells in parallel to the coiled wire around the metal.

Our next challenge was to build a lighthouse using a magazine, wire and a bulb. The aim was to hold a creme egg as far off the ground as possible and connecting the bulb to the top, extra oints were awarded if we were able to get our bulb to flash three times. The strongest and sturdiest lighthouses were made of three rolled up pieces of paper joining in the middle (like a tripod) and another rolled up piece of paper on top of the joint holding the egg. The way to get the bulb to flash was to connect it up but with one side of the wire quite loose and tapping the loose end.

Our final challenge was to create a solar powered boat. We designed the boat and chose the best propeller then charged up our capacitor and let timed the boat.

Throughout the day, all members of the team took part in a Fermi quiz where we had to estimate values to the nearest power of 10. These included the volume of air above the county of Yorkshire, the amount of handcuffs needed to travel the distance of the moon's orbit around earth twice and how many Smarties weighed the same as a hippo. The bonus question was to estimate the amount of Smarties in a container. We were one of five teams to get closest to the answer to the bonus question which was 433 and we one 433 Smarties to share between us.

We didn't win but we definitely had a great time! Thank you to St Peter's for hosting the event and all of the sponsors.

York University: Astrophysics

14/6/15

On Sunday, York University were having an Astrophysics exhibition with lots of things to see as well as lectures given by staff at the university.

We saw a lecture entitled "In Space No-one Can Hear You Scream!" by Katherine Leech. She started off by explaining about escape velocity (the speed things have to travel to escape earth's gravity and fly off into space) using an online Newton's Canon. She demonstrated that if a cannonball is fired into the air at 5000 m/s, this is only fast enough to send it into orbit around earth. It must travel at a speed of around 10 000 m/s to actually be able to get into space.

Secondly, we talked about why astronauts at the ISS feel weightlessness. A common answer for people to give is "there is no gravity in space" but this is incorrect! Of course there is gravity in space, it is what keeps the moon in orbit around earth and the earth in orbit around the sun! Actually, astronauts feel weightless because they are constantly falling but they don't hit the ground because the earth is constantly moving away beneath them at the the same speed.

Thirdly, we discussed what can go wrong for astronauts in space. Space is a vacuum so there are no air particles. Obviously, this means that astronauts who don't wear a space suit won't be able to breathe in space! Another problem that astronauts face is that if their helmet cracks, their tears and saliva will boil in their body. This is due to the lack of air particles as well. To demonstrate this, we watched an experiment where we put a beaker of normal, cold water into a vacuum, what we saw was that the water started boiling! This wasn't because the water was hot, but is actually because there are no particles pressing down on the water so the water molecules can escape the liquid. On earth
(where there are particles pressing down on the water) we have to transfer energy to the water
molecules to make sure they are able to escape when we're demonstrating evaporation, for example.

The problem that really concerned me was that your lungs can explode in your chest if you're in
space without a suit! We watched a balloon inside a vacuum and it slowly expanded until it popped, again this is due to the lack of air particles. Another problem is that if you are in trouble in space and you need assistance, without air particles or a radio you won't be able to get help! This is because sound is a wave, and it needs a medium to travel through. If there are no air particles, the waves can't transfer their energy to each particle and sound won't travel.

The final thing we covered in the lecture was how your oxygen supply can be cut off in space. This is due to how cold it is and this extreme temperature can crack the tube your oxygen travels through.
We watched a rubber tube get dipped into liquid nitrogen (reaching temperatures of around -210°C) and it shattered when hit on the table! We ended the lecture by saying thank you to Katherine Leech. 

Next, we walked around the exhibition and saw numerous things. The first thing was a telescope that looked like Galileo's which is a telescope that uses lenses, it was extremely long!

Next to it, we saw a more modern telescope which was much shorter, and used mirrors to let in light. 

We attended a second lecture in the afternoon called 'Let There Be Light' all about the types of light the sun emits. We had a tour of the Electromagnetic Spectrum starting with radio waves and ending with gamma rays. 

Radio waves have the shortest wavelength and we use them for everyday communication. 

Next are microwaves which we use to cook food.

Infrared radiation is next. We use it in infrared cameras to see things that are hot.

In the middle is visible light which we see from the sun. This can be split into the rainbow (spectrum).

Ultraviolet is next. This is one of the types of radiation that causes cancer.

X-rays are used to view broken bones for example, in large amounts this can cause cancer.

Finally, gamma rays. These have the most energy and also can cause cancer.

We also learned how the sun emits visible light. This is due to nuclear fusion, when the nuclei fuse, it releases large amounts of energy in the form of light and thermal energy. Nuclear fusion is also the reason why the sun doesn't collapse in on itself due to its huge mass. The sub-atomic particles that get released push up against the sun and applies an outward force that balances gravity.

We booked a tour into two planetaria. The first had a short video about the new James Webb Space Telescope and also about the types of light telescopes use. The second was all about navigation with the night sky using the programme 'Stellarium'.

I had a great day and hope to go there again!

Quantum Universe Lecture

9/6/15

I attended a lecture at St Peter's school where Professor Jeff Forshaw (co-author of several books with Professor Brian Cox) gave a talk on quantum physics.

It was a thoroughly enjoyable talk and I absolutely loved it! We learned about how electrons behave, quarks, leptons, the Higgs boson, and many more. It was such a fascinating talk, especially for a physics geek like me!

At the end of the talk, we had the opportunity to ask questions. This was great because it showed how little we actually know, people were asking Professor Forshaw numerous questions and sometimes, the answer was "I don't know," which really just shows how much there is yet to discover.

After the talk, I bought a book by Professor Forshaw and Professor Cox entitled 'Why does E=mc²?" Professor Forhsaw was signing books and I got the opportunity to talk to him! I got mistaken for an A Level student (I'm only 13)! I got my book signed too!

Holgate Windmill

24/5/15

Today, I visited a windmill which was just recently repaired. The odd thing about this windmill is that it has five sails, the usual number is four.

 

When I went inside, it occurred to me that so much engineering, maths, and physics went into the design of this windmill. I'll describe what the windmill was like from top to bottom as it's more logical that way.

 

The top floor was where we could see the gears of the windmill working but we weren't allowed to go right up to them in case they suddenly started moving. Windmills are extremely clever as they change the direction of motion using a series of gears. They convert the motion of the sails to motion which can turn the grindstones to grind the wheat. They do this using a crownwheel and a pinion. The pinion is turned by the sails and the crownwheel meets the pinion at angle to turn the grindstones.

 

The next floor was the bin floor where gravity is taken advantage of. Grain is stored on this floor and when the grindstones run out of grain, this where they refill it, by letting the grain fall down the bins and into the grindstones.

 

The last working floor is the stone floor where the grindstones are located. This where the grinding of the grain happens. The two grindstones that rotate to cut the grain have to be the thickness of a tissue paper to be able to cut the grain properly because if they were any further apart, it wouldn't grind the grain and if they were too close, you would end up with bits of ground down rock with the flour as well.

 

As a souvenir of the fascinating trip to the windmill, I bought flour from the mill itself as well as yeast! Can you guess what I made? (If you would like to visit this windmill, here is their website http://www.holgatewindmill.org/index.htm)

 

 

York University Astrocampus Visit

Today (May 21st) I went to visit the Astrocampus at the University of York. I had an excellent time and really enjoyed looking at the telescopes and listening to the talks.

Our visit began with a tour of the night sky, unfortunately (and to my extreme disappointment) the summer time sky prevented us from looking at the stars, planets and constellations so we used a programme called 'Stellarium' to look at the night sky (Link to Stellarium website). We had a look at Ursa Major and identified where the North Star (Polaris) was which was a lot of fun with Stellarium! Another great thing about the programme is that you can look at the planets in so much detail - the bands of cloud on Jupiter were visible, it was as if I was there!

 

 

After the tour of the night sky, we went outside to have a look at the many telescopes at the site. We had a look at the sun through two small ones (with a filter to keep our eyes safe of course), then went to two huge radio telescopes (one detected radio waves from hydrogen and the other detected waves from methanol). Next we saw a telescope station with an array of telescopes with mirrors rather than lenses (one of them even had a GPS system built into it so it could tell you exactly where you were and things of note in the sky at the time you were there!) and finally we went into a huge observatory with a 14 inch telescope (pictured below) and a revolving dome (I was like a child in a sweetie shop)!

 

 

 

 

 

To conclude, we went back into the building to listen to a talk on the sun. The sun has extremely random magnetic activity, this causes solar flares when magnetic fields in the sun pointing in opposite directions interact. Also the sun has sunspots - these are cooler areas of the sun which are also darker due to the lower temperature. Finally we learned about how the sun makes its energy, through nuclear fusion (a topic I'm slightly obsessed with).

 

If you ever visit York and are interested in Physics, Astrophysics, Astronomy or just an educational and fun evening, visit the Astrocampus - it's definitely worth it! (Astrocampus Website)