Subject: kepler motion applet Date: Thu, 23 Sep 1999 06:00:13 -0700 (PDT) From: lee taishen <leetaishen@yahoo.com> To: hwang@phy03.phy.ntnu.edu.tw Dear Mr. Hwang, Referring to the kepler motion applet in the below add. http://www.phy.ntnu.edu.tw/java/Kepler/Kepler.html I find it very interesting. However, I have some difficulties when using the applet. 1. For second kepler law, the area of the shaded area and non-shaded area should be the same. However, there is no data showing what the area is. 2. for third kepler law, i observed that there is no indication of the period of the planet. There is this T value indicated in the applet but it is not the period. i would appreciate if you can explain what the T value is. thank you. best regards leetaishen