[題目] 一題普物

作者: spysea ( )   2011-06-09 16:04:36
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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