84. 4 relative velocity addition and accelerations 2. relative velocity addition and accelerations r=R+r dr dr dr dtdt dt Vpo+voo R Po-ap0ta if voo=constant, then a 84. 4 relative velocity addition and accelerations 3. Some topics of discussion OIs there really inertial reference frame? @Are space and time absolute or not? @The measurement of the time interva @The measurement of the space distance9 §4.4 relative velocity addition and accelerations 2. relative velocity addition and accelerations r = R+ r′ r r PO PO O O PO PO O O a a a v v v ′ ′ ′ ′ = + = + r r r r r r t r t R t r d d d d d d ′ = + r r r PO PO O O a a v ′ ′ = = r r r then if constant, O r r r′ r R r P O′ §4.4 relative velocity addition and accelerations 3. Some topics of discussion 1Is there really inertial reference frame? 2Are space and time absolute or not? 3The measurement of the time interval; 4The measurement of the space distance