实验器材：1cm厚的石膏板若干，质量为50g的鸡蛋数枚。

实验过程：无风环境下，将鸡蛋从楼上静止释放，砸中铺在草坪上的石膏板，记录实验现象。

    Today is Sunday. We don't go to school. So after breakfast I go to the park with some of my good friends. In the park, there are many people. They are doing exercise. Some women are dancing. Some people are playing badminton. Some girls are skipping, and some people are walking and running. Why do they work so hard? Because they want to be strong and healthy.