http://www.ck12.org Chapter 3. Forces
CHAPTER
3 Forces
Chapter Outline
3.1 Newton’s First and Second Laws of Motion
3.2 NEWTON’STHIRDLAW OFMOTION
3.3 MASS VERSUSWEIGHT
3.4 FRICTION
3.5 REFERENCES
What is a force? A force is a push or a pull. The movement experienced by the man above can be explained as
a combination of forces. Though gravitational force pulls him downward, the water shooting out of his jet pack
provides a force pushing him up. Sir Isaac Newton (1642–1727) was the first to study forces as the cause for
acceleration. The connections he understood are known as Newton’s Laws of Motions, and are explained in this
chapter.