南开大学：《力学》课程教学资源（PPT课件，英文讲稿）Chapter 2 Dynamics

(2). Vback = v Perfect elastic collisionQuestion: how about the pressure?Solution:Each particle's impulse exert on wall(1). Ap = mv(2). △p = 2mvInterval: △tNS2mvAtvAsnx7mv

v v (2). back = Perfect elastic collision. Question: how about the pressure? Solution: Each particle’s impulse exert on wall. p = mv (2). Interval: p = 2mv (1). t       mv mv tv sn 2 s

2mv2nmv?AFE-APOyAsnxnmy?As△tmyAverage: A =< A >= A(t)dt. prediction : T oc-mv2Relevant problems(1).F When the hole was notholemade up, F is bigger thansea waterthat when the hole wasWhy?boat

   =   = 2 2 2 nmv nmv s F P Average:  = = T A t dt T A A 0 ( ) .  1 p 2mv F v sn t mv   = =     Relevant problems: sea water boat F hole (1).  When the hole was not made up, F is bigger than that when the hole was . Why? 1 2 : 2 prediction T mv 