作者spysea (命中註定的好天氣 )
看板Physics
標題[題目] 一題普物
時間Thu Jun 9 16:03:24 2011
A certain cocket(mass:m), which has an initial speed of zero,
is lauched vertically upward from the earth's surface with uniform thrust
of F.
The thrusr is terminated at time t0 following launch.
Afterwards, what is the highest altitude above the earth attained
by the rocket?
Assume that the change in m and the change in g due to height are negligible.
答案是: F(F-mg)t0^2/( 2m^2 g)
請問一下這題要怎麼解呢?
我是用V=V0+at
V=(F-mg)t0/m
mgH=1/2 mV^2
然後把V=(F-mg)t0/m代入上式
可是這樣算出來是錯的
煩請版友指正
感謝
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1F：推 a0184030:t0是推進器中止的時候 但是速度還是往上的 仍然上升 06/09 20:05
2F：→ a0184030:mgH=1/2 mV^2整個是錯的 表示你沒看懂題目 06/09 20:07