John Kevany Science

10/08/2026

What happens when a physics teacher teaches maths? Lots of questions.

We all (hopefully) follow BIDMAS. Why? Why couldn’t we live in a world of SAMDIB, i.e. BIDMAS backwards, where 2 + 3 × 4 = 20.

Maths would still work as would physics. We’d just have to write equations differently.

I don’t even like BIDMAS as many students take it literally left to right with the D before the M, and the S comes last.

Let’s call it BIMA.

Brackets
Indices
Multiplication/division
Addition/subtraction

Much clearer.

Discuss.

15/01/2026

https://youtu.be/DB8i1kyXkWc?si=SmuiJXV79hIm39QE

Interstellar, the 2014 movie. Science fact or science fiction?

Planets where one hour is seven years on Earth? Black holes? Wormholes?

Crazy Hollywood or real physics? How much of Interstellar is science fact, and how much is science fiction?

1. A planet where one hour equals seven years?

Science fact 👍

This is time dilation (stretching). Near a massive object like a black hole, gravity is so strong that time itself runs more slowly. The astronauts on Miller’s planet experience one hour while years pass elsewhere. This is real physics, predicted by Einstein’s theory of relativity. It’s used on a smaller scale in everyday technology like satellites.

2. Black holes?

Science fact 👍

Black holes form when massive stars collapse under their own weight. They’re so dense, with gravity so strong, that not even light can escape.

3. Wormholes?

Science fiction (for now) 👎

Einstein showed they are mathematically possible, but there is no evidence they exist.

4. Solving gravity? Professor Mann’s (Michael Caine) equation?

Science fact 👍 but the most humbling part 👎

We can predict gravity with amazing accuracy, but despite it being over 300 years since Newton and about a century since Einstein’s findings, and with all the research and technology, we still don’t know what gravity actually is.

Not even physicists know everything. There’s so much still to learn.

All of these ideas start to appear in GCSE physics and are explored properly at A level.

Physics is far from boring! It’s how we understand time, space, the universe, and it leads to proper careers and serious opportunities.

11/05/2025

☢️ What is nuclear fission? (6 marks)

Common GCSE physics paper 1 writing question

Not a bad effort here from HBO’s Chernobyl, but the actor (playing the late Professor Valery Legasov, RIP) only gets 5 marks.

Watch the clip. What’s wrong with his explanation?

Comment below with an answer. It’s not about isotopes, etc. This is a GCSE-level question

Message me at m.me/thejkscience to find out how real-world physics/engineering is helping my current year 10/11 GCSE physics students 🙂

💥 Chernobyl: A Blast From the Past, A Haunting Legacy 💥Get ready to dive into one of the most intense, spine-chilling chapters of history with Chernobyl. T...

03/05/2025

14/03/2025

A physics degree opens doors to endless career opportunities - but navigating them can be overwhelming for physics students and recent graduates. In this Physics World Live panel, career experts will help you explore your options and plan your next steps.

📅 Wednesday 9 April 2025
⏰ 3pm BST

Speakers include:
⭐ Crystal Bailey (American Physical Society)
⭐ Dr Tamara Clelford (IOP)
⭐ Araceli Venegas-Gomez (QURECA)
⭐ Tushna Commissariat (Physics World)

➡️ Register today: https://bit.ly/3FpVUic

01/03/2025

https://youtu.be/SHYxhmpN_gU?t=14

𝗪𝗔𝗟𝗟-𝗘 𝗮𝗻𝗱 𝘁𝗵𝗲 𝗠𝘆𝘀𝘁𝗲𝗿𝘆 𝗼𝗳 𝘁𝗵𝗲 𝗣𝘂𝘀𝗵𝗶𝗻𝗴 𝗧𝗮𝗯𝗹𝗲!

Remember in WALL-E when he zooms through space using a fire extinguisher? He pushes gas one way, and it pushes him the other way. That’s Newton’s Third Law, i.e. for every action, there’s an equal and opposite reaction.

But in school, I remember being baffled when told that if we push a wall, it pushes back, or if we put a 10 Newton weight* on a table, the table pushes up. How can walls and tables push back? They don’t have muscles!

When you place a 10 Newton weight on a table, the force of gravity pulls it down. This creates a downward force on the table’s surface.

However, the table’s material is made of atoms held together by electromagnetic forces. As the weight presses down, the atomic bonds compress slightly and generate an elastic restoring force. This force, known as the normal contact force, acts perpendicular to the surface and balances the weight.

So, even though a table is inanimate, its atomic structure resists deformation and provides an equal and opposite reaction force, obeying Newton’s Third Law. That’s why your drink doesn’t fall through the table!

𝗦𝗽𝗲𝗮𝗸𝗶𝗻𝗴 𝗼𝗳 𝘀𝘁𝗿𝗼𝗻𝗴 𝗳𝗼𝗿𝗰𝗲𝘀, 𝗺𝘆 𝗚𝗖𝗦𝗘 𝗣𝗵𝘆𝘀𝗶𝗰𝘀 𝗴𝗿𝗼𝘂𝗽 𝗰𝗹𝗮𝘀𝘀𝗲𝘀 𝗳𝗼𝗿 𝟮𝟬𝟮𝟱/𝟲 𝗮𝗿𝗲 𝘀𝘁𝗮𝗿𝘁𝗶𝗻𝗴 𝘁𝗼 𝗳𝗶𝗹𝗹 𝘂𝗽! 𝗜 𝘀𝘁𝗶𝗹𝗹 𝗵𝗮𝘃𝗲 𝘀𝗽𝗼𝘁𝘀 𝗮𝘃𝗮𝗶𝗹𝗮𝗯𝗹𝗲 𝗳𝗼𝗿 𝗲𝘅𝗮𝗺 𝗽𝗿𝗲𝗽𝗮𝗿𝗮𝘁𝗶𝗼𝗻 𝗯𝗼𝗼𝘀𝘁𝗲𝗿 𝘀𝗲𝘀𝘀𝗶𝗼𝗻𝘀 𝗶𝗻 𝟮𝟬𝟮𝟱, 𝘀𝗼 𝗶𝗳 𝘆𝗼𝘂 𝗻𝗲𝗲𝗱 𝘁𝗵𝗮𝘁 𝗳𝗶𝗻𝗮𝗹 𝗽𝘂𝘀𝗵 𝗳𝗼𝗿 𝗮 𝟳-𝟵 𝗴𝗿𝗮𝗱𝗲, 𝘁𝗵𝗲 𝗲𝘅𝗮𝗺𝘀 𝗮𝗿𝗲 𝟭𝟮 𝘄𝗲𝗲𝗸𝘀 𝗮𝘄𝗮𝘆, 𝘀𝗼 𝗻𝗼𝘄’𝘀 𝘁𝗵𝗲 𝘁𝗶𝗺𝗲!

Drop me a message if you're interested! 📩

* 𝙍𝙚𝙢𝙚𝙢𝙗𝙚𝙧, 𝙬𝙚𝙞𝙜𝙝𝙩 𝙞𝙨 𝙖 𝙛𝙤𝙧𝙘𝙚 (𝙢𝙚𝙖𝙨𝙪𝙧𝙚𝙙 𝙞𝙣 𝙉𝙚𝙬𝙩𝙤𝙣). 𝙈𝙖𝙨𝙨 𝙞𝙨 𝙢𝙚𝙖𝙨𝙪𝙧𝙚𝙙 𝙞𝙣 𝙆𝙞𝙡𝙤𝙜𝙧𝙖𝙢𝙨. 𝙏𝙝𝙖𝙩 10 𝙉𝙚𝙬𝙩𝙤𝙣 𝙬𝙚𝙞𝙜𝙝𝙩 𝙬𝙤𝙪𝙡𝙙 𝙗𝙚 𝙖𝙧𝙤𝙪𝙣𝙙 1𝙠𝙜 𝙢𝙖𝙨𝙨 (𝙤𝙣 𝙀𝙖𝙧𝙩𝙝).

04/09/2024

Had a foray into teaching Level 2 Functional Skills Maths to a mature student recently. A pass is supposedly equivalent to a GCSE grade 5, but I think Level 2 is way harder, especially when the students will often be much older. My student passed at the third attempt. One issue is many questions are very wordy.

Have a look at this question. A student will need to know the formula for circumference and convert the units (after applying a scale of 200). My student was also a non-native speaker of English and wasn’t sure what a bandstand was. It’s not important, but it all adds to the cognitive overload.

I got the answer (around £168), but it’s not easy to teach. Feel free to have a try and see what these students have to go through. I’ll show workings in a day or two.

Real World GCSE Physics Success

Want a GCSE physics grade 7-9 in 3 months?

23/02/2024

Here’s a question/answer you might not find on the internet. I couldn’t find a ready-made answer.

“Why aren’t house radiators black?”

I’ll answer in a few days. It’s actually not because of aesthetics.

Visible light is made up of different colours, and objects have colours because of how they absorb or reflect this light. The leaf of a plant, for example, absorbs red and blue light but reflects the green light. Hence, the leaf appears green in colour.

Black objects absorb all visible light, which is why they appear black. So where does all that energy go? It can’t just disappear. It’s converted into heat energy, and that’s why black objects feel warmer in the sun.

So black objects absorb heat (infra red radiation) well, but they also emit this heat well too, far better than a white surface will.

So why aren’t radiators black?

13/12/2022

https://youtu.be/ifAY5tbYDmQ

Nice easy question, or is it?

Rather than reinvent the wheel, I wanted to use some words from the internet to explain this to an A level physics class. But all I found on the internet were mistakes and misconceptions. Not one correct answer out there in cyberspace.

So I had to write my own explanation. The question is, why do the children on this Gravitron Ride feel like they're being pushed into the wall?

The answer is in the comment below.

22/11/2022

There’s a mistake on this A level physics question about thermistors. Thermistors are semiconductors, so their resistance increases with lower temperatures.

A is correct, but there is also another statement (B, C or D) which is also correct. Which one?

I’ll show the answer (and why) in a couple of days.