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| 分享使你變得更實在,可以使其他人感到快樂,分享是我們的動力。今天就來分享你的資訊、圖片或檔案吧。 本帖最後由 Ameril 於 2010-9-16 04:05 AM 編輯
A water-rocket accelerates from rest at ground level at 5.0ms-2 vertically upwards for 30s and then it undergoes free-falling in air. Calculate
(a) the speed and the height of the rocket at 30s after launch
speed = Acceleration * time = 5.0 m/s^2 * 30 sec = 150 m/sec
position = 1/2*acceleration*time^2 = 5.0 m/s^2*30^2sec^2 / 2
= 2.5*900 = 2250 meter ... |
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