This is a good introduction to (or refresher on) an important unit in high school physics. That said, I do wish the author had recognized the difficulties of writing in a language that is not his own. He could have used this opportunity to learn English more thoroughly by asking a skilled editor for corrections, beginning with removing the apostrophe from the title.

Instead, the article looks as if it wasn't proofread and may, therefore, be wrong on details as well. For example, the author writes that force is a vector quantity because it has "magnitude as well as direction." In standard usage, the distinguishing feature does not go in the "as well as" phrase; it goes in the principal phrase: Force is a vector quantity because it has direction as well as magnitude. (Scalar quantities, e.g., energy and speed, have magnitude but not direction.)

I would urge the author to repost an edited version of this otherwise useful primer.