Hi; Yes I’m still here. Even though I have stopped teaching physics I haven’t stopped thinking about it. I have a lot of free time so fill it with different activities. It is strange how my life teaching physics influences how I go about everyday tasks like baking. Baking can be done by mixing accurately measured quantities or by the way it looks feels. I am definitely a 'look and feel' baker. Here is my recipe for croissants.

Over the past year there has been a lot of talk about AI. If I was still producing material for this site I would probably use it quite a lot. I thought I would test it out by seeing how good Chat GPT is at clearing up some common misconceptions, for example this common misconception about Newton’s 3^rd law.

If every action has an equal and opposite reaction why does a body accelerate when a force is applied?

This is my explanation:

This is a common misconception made worse by this simple statement of Newton’s 3^rd law. A better statement would be that if body A exerts a force on body B then body B will exert an equal and opposite force on body A. Using this statement we can see that there are 2 bodies involved and this is ALWAYS the case.  If there was only 1 body in the universe it would never move, as to make it move would require an unbalanced force and that would mean there must be another body.

Examiners like to play on this misconception and will ask questions like “When a person pushes a car according to Newton’s second law the car will push back with an equal but opposite force. Why then does the car start to move?”. The answer is that the force exerted by the person is applied to the car but the force present according to Newton’s 3^rd law acts on the person. There is therefore only one force on the car. This is unbalanced so according to Newton’s 1^st law the car will accelerate, i.e. its velocity will change from zero to something.

And this is ChatGPT:

"Great question! The principle you're referring to is Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. But this law can be a bit tricky when you start thinking about it in terms of forces and acceleration.

Here’s the key: the reaction force does occur, but the reason a body accelerates when a force is applied is due to the difference in the forces involved and the way they act on different objects. Let’s break it down:

1. Action and Reaction Forces: According to Newton’s Third Law, when you apply a force on an object (like pushing a car), the object applies an equal and opposite force back on you (the car pushes back on you with the same force). So, if you push the car with a certain force, the car pushes back on you with the same magnitude of force but in the opposite direction.
2. Why Does the Object Accelerate? The reason the object accelerates is that the force you're applying to it is not counteracted by the same force within the same object. Instead, that reaction force goes into the object you're pushing against, not into the object you're applying force with. So the object accelerates in the direction of the force you're applying.

For example, when you push a car, the force you exert on the car causes the car to accelerate in the direction you're pushing. The car does exert an equal force on you (the "reaction"), but that force acts on you, not on the car. Your acceleration is much smaller compared to the car’s because your mass is usually much smaller, so you experience a much smaller acceleration due to the same force.

3. Force and Acceleration (Newton’s Second Law): The second law, F = ma, explains how acceleration works. The force you apply causes an acceleration, but how much the object accelerates depends on its mass. The car has more mass than you, so for the same amount of force, it accelerates less than you would.

In essence, both the action and reaction forces are there, but they don’t cancel each other out because they act on different objects. The force applied to the car causes it to accelerate, and the force the car applies to you doesn’t stop you from moving; it’s just why you experience a different acceleration. Does that help clear things up?"

It’s interesting how ChatGPT starts with the compliment “Great question” which makes the student feel good. Makes it sound more personable than my “this is a common misconception”. The answer is clearly explained and correct.

Answering students' questions in class lets the students know that you understand the subject, giving them confidence in your knowledge. This forms a bond between you and the student and a relationship is formed. The student trusts you and will listen to your answers and explanations. When I started teaching I was about the same age as my students and they listened to what I had to say. After 20 years of teaching, I was the same age as their parents and it took more time to convince them that I knew anything. After 40 years I was the same age as their grandparents and they saw me as a wise old man trusting every word I said.

During my last 8 years of teaching, I changed from a front-of-class teacher to a more student-centred approach. My students would follow the course online, working through the activities on this website. I would sit at the front and answer individual questions but rarely spoke to the whole class. For those of you who don’t know, this was because I got Parkinson’s disease which has a complex and individual set of symptoms that made it difficult for me to stand at the front and perform in the way I used to. Some of you will have attended one of my workshops during this time. I would sit at the front and Emma would present all of the material that I had produced. I would chip in with funny anecdotes whenever I felt like it and answer questions. Very much a double act. Without the stress of presenting I was totally relaxed and as a result more approachable I was having fun and as a result everyone was having fun. The feedback from participants reflected this. I didn’t really do anything but got lots of good feedback. If there is a good learning environment in the class then learning will take place and it is up to the teacher to create that environment. When using a student-centred approach it is important that students feel comfortable to ask the teacher questions. If a student arrived late and I confronted them in an angry way it would kill the class. ("Oooh, better not ask him anything today, he’s in a bad mood.") I have to admit that sometimes I would not say a word for the whole hour and a half - not because the students were scared but because they were engrossed in the activity. In some ways I made the activities too good.

The system worked, the students learnt physics and did well in the exam. In theory, the weaker students should benefit most from this approach since they can ask questions and get individual help but this wasn’t the case. The students who asked most questions were the brightest ones. The weakest students would simply copy out the material from the activities without answering the questions. They didn’t know that they didn’t know. Looking back maybe I should have been more proactive but my illness made the whole situation difficult. Another problem was that the students put me on a pedestal. I wrote the book, I created the website. They thought I was some sort of genius. I once heard a student say to another as they walked past my room “He’s supposed to be the best teacher in the school”. Hmm. I taught 6 classes but didn’t do much more. I spent all the time at work in my classroom, I ate lunch on my own. I even had a bed so I could sleep between classes. I only had contact with students who took physics. I look a bit strange. Fairly scruffy, uncombed, unshaved, expressionless face, head bent forward, shuffling gate, leaning to the left and of course the shaking hand. The shaking got worse if I got stressed. I would sometimes be sitting with a student trying to explain something and they wouldn’t understand so I would try another explanation. Sometimes I would tie myself in knots and start to get stressed. This would make my shaking get worse and the student would keep glancing at my hand. I always explain things with diagrams but Parkinson’s made my handwriting small and my diagrams microscopic. My solution was to abandon my attempt and try again in the calm of my own room at home. I would video the explanation and send it to the student. This resulted in hundreds of videos.

Parkinson’s isn’t just a shaking hand, there are many symptoms both physical and cognitive. To slow down the physical progression I rock climb and to monitor the mental side I do the Guardian crossword. I try it everyday but I don’t always complete it. I am getting better at crosswords but not anything else. I find following electrical circuit diagrams and maps problematic. Typing is also difficult. I wrote this early in the morning when my hands were working but the window has now closed. I will have to finish another day. Now it’s time to get out in the garden and move some rocks.