2.1 Forces.
Understandings:
  • Objects as point particles
  • Free-body diagrams
  • Translational equilibrium
  • Newton’s laws of motion
  • Solid friction
Solid friction.
Free-body force diagrams.
Wikipedia - free body force diagrams

S-cool - Forces
Newton's laws of motion.
S-cool - Forces.

Walter Fendt - Newtons 2nd Law Expt
Newtons 2nd Law (includes how to set up a friction compensated runway) - Force and acceleration practical

Veritasium video - Three incorrect laws of motion

xkcd - What if - Everybody jumps

Whack the penguin