Two men are walking in the park. One is Mr. Brown, a worker, the other is Mr. Black. Mr. Brown is going to a chair. It is next to the road. Mr. Black is after him. Mr. Brown finds Mr. Black. Now Mr. Black begins to walk faster (更快). Because he wants to get to the chair before Mr. Black. Now Mr. Black begins to walk faster because he also wants to get to the chair first. Then they both run. Mr. Black runs faster than (比) Mr. Brown. So he gets to the chair first and sits down on it. Mr. Brown runs after Mr. Black. When he gets to the chair. He sees Mr. Black sitting on it. He is sorry to show a notice(通知)with the words“Wet Paint(油漆未干)”to Mr. Black. Now Mr. Black knows why Mr. Brown is going to the chair.
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。
实验序号
楼层
实验现象
1
15
鸡蛋破碎，石膏板凹陷且出现一圈圈螺旋状的裂纹
2
25
鸡蛋破碎，石膏板被硬中的地方出现小坑且破裂
3
鸡蛋破碎发出巨响，石膏板被击穿
小华将甲、乙两组生长状况相同的水稻幼苗，分别用等量的土壤浸出液和蒸馏水在同一环境下进行培养。一段时间后，发现甲组生长正常，乙组植株矮小，叶片发黄。此实验说明（ ）
