勿理人
2018-4-5 23:14:27
如果你未學好好DSE野,就唔好學d out-C野住。
一般而言,friction oppose the motion。
詳細d講,friction opposes the tendency of change of motion between two contacting surfaces。
如果無friction,the object tends to move on a straight line,相對嗰center就會向外(意思係遠離左嗰center),所以friction 向住center
一般,老師/出面教嘅方法,
The object undergoes a circular motion.
There must be a net force (centripetal force) towards center. Since the friction is the only force parallel to the table, it must be towards center
但咁解釋其實係倒果為因,知道左結果,先判斷嗰因,但如果你上面解釋唔明,就用呢個黎解釋