force exerted on the ball by the sand係向上定向下既力? 如果係向上..呢個力大過weight..咁個波唔係向上運動咩? 佢仲向下行?? 如果係向下既力..姐係同weight平行?? 唔係好明act係ball既力 小霞的fans 發表於 31/3/2010 12:58 PM
force exerted on the ball by the sand是向上的力。 Motion不一定跟Net force同方向的，跟Net force同方向的是acceleration。 所以向上的net force會使原本velocity向下的波decelerate。 Requiem 發表於 30/3/2010 06:46 PM
有CARDBOARD時: System的風扇比力空氣向後流動，空氣比reaction force比成個system向右 空氣撞上CARDBOARD，SYSTEM的CARDBOARD比力空氣，空氣會比番reaction force比成個system向左 =>BALANCE OF FORCE ON THE SYSTEM
An object slides down a sooth plane from rest.which of the following graphs shows the variation of kinetic energy with time. 我唔係問個graph,..係問d step.. K.E.=1/2mv^2 by v=u+at =1/2m(u+at)^2 =1/2ma^2t^2 since 1/2ma^2 is constant,,K.E. varies with t^2
An object slides down a sooth plane from rest.which of the following graphs shows the variation of kinetic energy with time. 我唔係問個graph,..係問d step.. K.E.=1/2mv^2 by v=u+at ... 小霞的fans 發表於 3/4/2010 02:47 PM
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