Force,Acceleration同埋Velocity

Q: 個波離手之係係咪就唔會再向前方加速?
Yes. The ball will no longer be affected by the hand after it leaves it (the hand). Hence, the velocity of the ball remains the same. But its subsequenct motion is affected by gravity.

Q:而本書成日都話一個物體喺拋出黎ge時候initial velocity 己經係某個數字
The given "initial velocity" is the velocity attained by the object after it has been accelerated by an external agent e.g. a hand).

個波離手之係係咪只會均速向前方運行,而非向前加速?
(唔計風阻造成的減速同地心吸力的向下加速)
如果唔計風阻和地心吸力, 而個波又已經離手, 即再沒有外力, 也不會加速, 只是以均速向前。

但係一個物體ge velocity由(未拋)靜止開始唔係應該係0咩
係唔係離手前發力個一刻個velocity已經由0加速到嗰個value
物體未離手前已經被隻手加速, 直至離手前一刻, 已有一個速度, 也就是本書話既 initial velocity.