Japanese students do well on the Pisa tests, and they use textbooks. So I bought a Japanese high school textbook to see what was different.

My daughters were instantly attracted to the cover – the book has a manga feel. Inside and out, the book does not feel like an English physics textbook. There is so much text.

I had hoped that I would be able to work out the idea from the diagrams and possibly the equations. I could, but there were so many more words than that.

Google Translate has an image feature, which translates Japanese into English. It was a little fiddly, and I’m not sure the translation is great, but it offers a fascinating insight into Japanese textbooks, which I thought I’d share.

Here is the translation:

Theme 4

What is gravity?

Gravity works on all objects. The earth will pull objects even though they do not touch objects directly. Shall I pursue this gravity for a while?

Step 1: Why do you write gravity as mg?

Let’s explain why mg is gravity here. There is a ball here (Figure 2-9). Let’s drop it. This state is called “free fall”. If you examine how the object falls, objects of any weight will fall at the same speed (but in a completely vacuum state). This was discovered by Galileo more than 400 years ago. The fact that any object falls at the same speed means that the acceleration of the object is the same. When measuring the magnitude of the acceleration, we found that all objects fall at an acceleration of 9.8 (m / s). Since acceleration is always 9.8 (m/s2), this is written as g and it is called “gravitational acceleration”. Let’s write the equation of motion of the falling ball. Let gravity be F.  I want to know exactly what this F is like, but it is outside the scope of physics I (the law of universal gravitation studied in Physics II is the answer). However, the acceleration a on the left side of the equation is empirically 9.8 (m/s2) meaning g, so the left side is expressed as mg and mg = F (gravity).

In other words, without knowing the law of universal gravitation, gravity is acceleration. Writing gravity as mg is the result of using the equation of motion. I think I understand the reason for writing gravity as mg, but I still have the question, “What is this gravity (universal gravitation in the first place)?” It is a deep problem that is not yet clarified by modern physics, but in high school physics, let’s do this.

I love the chatty but rigorous style. I like the foreshadowing of Universal Gravitation in book 2. I now want to know how well a Japanese student could read this and understand it.

I think there are a couple more blogs here. I’m curious about the questions (I hope they are in here – I can’t tell until I scan more). I’m curious about the model answers.

If any of you know any Japanese physics teachers, I’d love to get in contact.

Ben