Dr. Brown Lecture Physics 53 7 Sep 2010 11:40 - 12:55 candy start inertial reference frames and symmetry use for inclined plane, atwood , conical pendulum recite-able Inertia, N2, Reaction symmetry / invariance -- time t' = t - t_0 -- \Delta t ==> dt' = dt ! same event length x' = x + x_0 ==> dx' = dx dx'/dt = dx/dt dv'/dt ... also invar under rotation ... inertial frame [mutually consist -- though circular defn] draws rest frame --> and const. velocity frame x = x' + v_0 t differentiate once and twice [accel measured is SAME in both!] N2 invarient under inertial frame changes what if non-inertial frame? v = v' + v_0(t) F_tot = ma = ma' + ma_0 "pseudo-forces" artillary, hurricanes, ... examples where accel frame needed for analysis problem 1. inclined plane -- frictionless 2. atwood 3. swing in circle [kung pow] -- constant speed -- a_r = v^2/r