[phy]今年A-level 的試題

dolphin_ice

之其中一條
大家估下la...

1. Give a situation of the following:

a) The acceleration is in 90degree angle to the motion

b) The object is stationary, but accelerating

c) The resultant force is 0, but the object is moving

abc666

b)設一物件向前行的速度是正,該物件一開始向後移動,然後向前加速,速度由負數到正數中經過速度是0的一瞬間,該物件是不動的,但在加速中
   Let the speed of he object when moving backward be negative. At the begining, the object is moving backward. then it accelerate forward.when the speed of the object changes from negative to positive, it pass through a point that the speed is 0. At that time, the object is stationary, but accelerating.

sapphire

比起HKALE實在是不夠看orz

a) Consider an object moving in a circular path. Its acceleration is always towards the centre of the path, and its direction of motion is tangential to the circular path. So its acceleration is always perpendicular to its direction of motion.

c) Consider a rod resting on a table. Then two forces, equal in magnitude but opposite in direction, are acted on the two ends of the rod, in the direction perpendicular to it. The resultant force acting on the rod is zero, but there is a torque causing the rod to have a turning motion.

[ 本帖最後由 sapphire 於 18/6/2007 16:33 編輯 ]

dolphin_ice

咦? 掂喎, 你2個.
*拍手*

fish

原帖由 dolphin_ice 於 19/6/2007 08:51 發表

                               
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咦? 掂喎, 你2個.
*拍手*

abc666是F5的~
(逃~~

sapphire

原帖由 dolphin_ice 於 19/6/2007 23:51 發表

                               
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咦? 掂喎, 你2個.
*拍手*

這些只是mechanics的basic concept......

原帖由 fish 於 20/6/2007 06:38 發表

                               
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abc666是F5的~
(逃~~

b和c也是CE生會的題目,其實還有幾個example的

[ 本帖最後由 sapphire 於 20/6/2007 10:30 編輯 ]

abc666

我記得a上堂有教過的但忘記了~.~

STEVE

c: an object falling with terminal velocity 計不計?

水龍蜥

看完有關resultant force既資料...

                               
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對呢一個唔係好明下...

abc666

有冇學過vector?