(急!!至少20點)唔識點寫自由落體實驗

實驗報告我有多年無寫過，相信寫得好過你是無可能。但要做"量度地心吸力實驗"，必須要注意實驗之高度，其實是很容易理解。一秒加速度9.8m，如果實驗使用1m高，理論上0.1秒已完成完成實驗，再以誤差值5%計(因誤差太大，實驗是無意義)，誤差只能在0.005秒之內，奧運之電子計時器都很難測出，更何況是使用手持計時器。以上是"阿sir話咁係正常"之原因。
第二會影響實驗結果是空氣之氣壓，即空氣密度。密度高代表浮力大，下降較慢。於是使用較重之下降物(mass)最有效。


2008-09-15 21:54:46 補充：
最後要補充，你想實驗達到之目的，才能設計出合適之實驗。例如想證明向心加速度為絕對的9.8m/s2，就要選擇幾個不同物質來做相同實驗。如想計算向心加速度為9.8m/s2，就要設定幾個不同高度，平均計算出來，但誤差就一定會大。

咁深o既 =_="

Propose

Free fall experiment to investigate the value of the gravitational acceleration constant g.

Procedure

Use a fixed height h, say 1m., and we put a sensor on the floor to measure the time need for free fall. (You can use stop watch, by your hand and eye to measure the time needed, but there will be error)

Repeat the experiment for several times, take the ave. time of the experiment.

Repeat the experiment by using different masses.

Try others height.

Result

The g measure should be around 9.8m/s^2, with an error ~5%, since there is air resistance, the g measured will be smaller. On the other hand, there will be error in measuring the time for free fall due to human reaction time.

In fact, g is vary on different part of earth, if the place is mainly rocky or ores underground, g will larger. You can try to find it on web.

To reduce error, you should repeat the free fall experiments for several time with same mass and height as 1 ave. data point. Then use a different height for next.
I suggest to use 3 different heights, 1m, 1.2m and 1.5m, and each 3 times, with a mass ~1kg metal ball.