Science with Arthur C. Clarke (1)

In Chapter 1 of 2010: Odyssey Two, Arthur C. Clarke wrote that an astronaut achieved a tenth of the speed of light in less than two minutes, and this meant an acceleration of about a quarter of million gravities.

Let's check. Here, I feel that the term "gravity" is not technical enough: Does it mean \( 1~\mathrm{ms}^{-2} \), the unit acceleration in SI units? Or g-force, an acceleration of about \( 9.8~\mathrm{ms}^{-2} \)?

Given that:

$$ u = 0~\mathrm{ms}^{-1} \\ v = \frac{c}{10} \approx 3.0 \times 10^7~\mathrm{ms}^{-1} \\ t=120~s $$

We have:

$$ a = \frac{v-u}{t} = \frac{3.0 \times 10^7}{120}~\mathrm{ms}^{-2} \\ \approx 250,000~\mathrm{ms}^{-2} $$

Indeed! The term "gravity" here should mean \( 1~\mathrm{ms}^{-2} \), which is the unit acceleration in SI units.

Notes for Pre-U Physics

I would like to write some notes (minimalist's notes) for certain topics in pre-university physics. I found that some students may be confused by the content of these topics, and sometimes I would also want to make a quick revision should I need them. That's why I write the notes and share them here.

I am a minimalist in writing notes: Just retain the essential definitions and concepts, while omit obvious applications and consequences. Keep in mind if you want to use them. 😊