apparent loss of momentum
2007-03-04 8:24 pm
當踢一個足球到牆的時侯,本身個足球有momentum,但係撞完個牆之後就停左,咁樣睇落去,momentum好似唔conserve,但係本書有話係conserve,為什麼?同地球mass大,v細有關?
回答 (3)
2007-03-04 11:55 pm
✔ 最佳答案
你講啱咗,我好sure你本書錯咗,Ken Chan教過由於淨力唔=零(足球和目標在,碰撞後均停止不動)由於淨力唔=零
地球施予目標的力
整個系統的momentum(i.e.足球+目標)唔conserve
至於地球mass大細已經無關,只要推斷出淨力唔=零,momentum就唔conserve。
要momentum conserve 就要考慮晒足球,目標(牆)和地球。
唔明嘅話再問過,我會盡量回答
2007-03-04 15:57:41 補充：
要考慮momentum conserve唔conserve唔係考慮mass而係淨力=唔=零
參考: Ken Chan 嘅學生
2007-03-18 5:47 am
我都係ken chan的學生
今日岩岩教完conserve -V-
今日岩岩教完conserve -V-
2007-03-04 10:27 pm
The momentum of the ball has been transfered to the earth.
m.v = MV
where m and M are the massess of the ball and earth respectively
v is the velocity of the ball before striking the wall
V is the velocity gained by the earth after stopping the ball
thus, V = m.v/M = (m/M)v
since M is very very large as compared with m, V is practically small and which is not observable
m.v = MV
where m and M are the massess of the ball and earth respectively
v is the velocity of the ball before striking the wall
V is the velocity gained by the earth after stopping the ball
thus, V = m.v/M = (m/M)v
since M is very very large as compared with m, V is practically small and which is not observable
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