f.4 phy既野
點解bys=ut+1/2at^2smaller deceleration requires a longer stopping distance既 ?
唔係應該shorter stopping distance 咩 ? 代數入去我係咁計到.. deceleration is -ve a deceleration is -ve a
【YU】 發表於 11-1-2009 14:54 http://www.nakuz.com/bbs/images/common/back.gif
咁例如我代u=0 ,, t=2 ,, a=-2
另1個u=0 ,, t=2 ,,a=-4
咁1個就係s=0(2)+1/2(-2)(2)^2
另1個就係s=0(2)+1/2(-4)(2)^2
第1條個答案係-4 .. 咁s姐係4啦..
第2條個答案係-8 ,, 咁s姐係8啦,,
唔係deceleration 比較大果個s比較大咩? 本帖最後由 wilson1993912 於 11-1-2009 15:49 編輯
用common sense去睇
Small deceleration=brake耐d
咁個stopping distance當然大啦
咁例如我代u=0 ,, t=2 ,, a=-2
另1個u=0 ,, t=2 ,,a=-4
咁1個就係s=0(2)+1/2(-2)(2)^2
另1個就係s=0(2)+1/2(-4)(2)^2
第1條個答案係-4 .. 咁s姐係4啦..
第2條個答案係-8 ,, 咁s姐係8啦,,
唔係deceleration 比較 ...
仲夏夜．戀人 發表於 11-1-2009 15:05 http://nakuz.com/bbs/images/common/back.gif
u點會係0呀= =
u係0既話停左係度仲洗鬼decelerate咩 同意樓上
u=initial velocity,如果u=0 姐係你一開始就冇motion咁你仲decelerate d乜野... deceleration is -ve a
【YU】 發表於 11-1-2009 14:54 http://nakuz.com/bbs/images/common/back.gif
可以+ve的
睇你定義邊邊係+ve
可以+ve的
睇你定義邊邊係+ve
wilson1993912 發表於 11-1-2009 16:39 http://www4.nakuz.com/bbs/images/common/back.gif咁樣的話實在有d搞屎棍 咁樣的話實在有d搞屎棍
piyopiyo 發表於 11-1-2009 19:29 http://nakuz.com/bbs/images/common/back.gif
有時題目會定埋比你去fake你.... 無論點定義方向都好,只要a is deceleration, 都一定係 opposite sign to s(braking distance).
piyopiyo都係由得佢搞吧~
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