Weight a minute

Since freshman chemistry is required for an engineering degree at North Carolina State, I’ve signed up for Chemistry 151 at Wake Tech, where it costs a mere $167, in order to transfer the credits to NCSU.

During our first class today, our PowerPoint professor put up a slide reading:

Matter — anything that has mass and takes up space

• mass —
  • SI unit of mass is the kilogram (kg)
  • 1 kg = 1000 g = 1 × 10³ g
• weight —
  • A 1 kg bar will weigh
    1 kg on earth
    0.1 kg on moon

When I spoke up to point out the error, she said 0.1 kg was what it said in the book.

Sigh. Seems like this course’ll be stultifying.

• 1 kg on Terra = 1 kg on Luna, because kilograms are units of mass, not weight. (Also, 1 lb. on Terra ≅ 0.2 lb. on Luna, because 1⁄6 g ≅ 0.17 g.)

[Ed.: My instructor mailed me a link to a discussion of mass versus weight. It makes a good case that pound is a unit of both mass and weight, but does not conclude that using kilogram as loosely is also correct.]

[Ed.: Despite this isolated the book is always right even when it isn’t incident, this course was not bad, and I enrolled for its successor with the same prof.]