Hewitt Drew-It! PHYSICS Screencasts
Newton's Second Law

17. Mass/Weight
Paul distinguishes between mass and weight in a video from his classroom, then breaks strings attached to a ball in ways that clarify the distinction.

18. Acceleration Units
Paul clarifies the equivalence of m/s2 and N/kg, and leads to Earth's gravitational field g.

19. Newton's Second Law
A video of Paul in the classroom is followed up with a discussion of force, mass, and the acceleration of freely-falling rocks.

20. Skydiver Problem
Paul poses and solves a problem involving Suzie Skydiver, who dives and attains terminal velocity.