[力學] 相對速度 小小問題
an 80-kg man is standing at the rear of a 240-kg iceboat that is moving at
4.0(m/s) across ice that may be considered to be frictionless . He decides
to walk to the front of the 16 m-long boat and does so at speed of 2.0
(m/s) with respect to the boat.How far did the boat move across the ice
while he was walking ?
根據老師課堂上講解大概的意思是.有一80-kg人在一16m長的冰船上行走.冰船與冰面
無摩擦.並以4(m/s)速度前進.問當人以相對於船的2(m/s)速度從船尾走到船頭.船則在
冰面行進多少距離 ?
解法是(線動量守恆): (240+80)*4=240*V+80*(2+V)
得V=3.5
故: d(距離)=v*t =3.5*(16/2)=28(m)
我的問題在於.為什麼相對速度在人走到船頭時速度還是代2.不是0 ?
人不是停下來了? 還是說純粹是因為只用討論到停下腳步的那"前一刻" ?
小小問題 有勞各位了!!
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