1. The distance ( h m) between a rocket a rocket and the ground after the rocket has taken off is given by h= 40t -5t^2, where t is the time (in second) after take-off.
(a) The distance between the rocket and the ground is h m after the rocket has taken off 5 seconds .Find h .
(b) Find the distance that the rocket travelled between the first second and the third
second
Maths
2008-08-12 10:05 pm
回答 (1)
2008-08-13 12:18 am
✔ 最佳答案
a. From the given condition,40(5) - 5(5)2 = h
h = 75
b. Distance travelled in the first second
= 40(1) - 5(1)2
= 35 m
Distance travelled in the third second
= 40(3) - 5(3)2
= 75 m
So, the distance travelled by the rocket between the first and the third second = 75 - 35 = 40 m
參考: Myself~~~
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