8.01SC Classical Mechanics
Age 18Sample18-year-old · 12 / intro

Inertial frames and ΣF = m a

From Newton's Laws of Motion · Peter Dourmashkin

Newton's first two laws are a statement about inertial frames: ΣF = d(mv)/dt, with superposition of real forces.

Original lecture on MIT OpenCourseWare

Before this sitting

Can you already do this?

Two quick checks on “you will be able to…”. Right on both and this sitting becomes mixed practice, not a lecture. Wrong is useful — we keep the full sitting.

  1. A student writes F = ma in a braking bus, using only gravity and normal force on a standing passenger, and cannot explain the lurch. The mistake is…

  2. m = 3 kg, F1 = 6 N east, F2 = 6 N north. |a| is…