问题 问答题

如图所示,在研究平抛运动时,小球A沿轨道滑下,离开轨道末端(末端水平)时撞开轻质接触式开关S,被电磁铁吸住的小球B同时自由下落.改变整个装置的高度H做同样的实验,发现位于同一高度的A、B两球总是同时落地

(1)该实验现象揭示了A球在离开轨道后在______方向上的分运动的规律;

(2)该试验装置的设计思想所体现的物理思维方法和实验方法分别是:______和______.

答案

(1)A、B两球同时开始运动,同时落地,说明两球在竖直方向上运动规律相同,B球做自由落体运动,

则该实验现象揭示了A球在离开轨道后在竖直方向上的分运动的规律;

(2)两球同时落地,两球在竖直方向上的运动效果相同,应用了等效思维;

实验中控制两球的下落高度相同、两球同时开始运动,应用了控制变量法.

故答案为:(1)竖直;(2)等效思维;控制变量.

阅读理解

阅读理解

        Your home is a safe place, right? Think again. Many serious accidents happen in people's homes.

Can you prevent these accidents? Yes. Many accidents happen because people are careless. So be

careful! Here are some tips about safety.

       ●Don't stand on chairs. Many people may fall off chairs and hurt themselves.

       ●Keep the floor dry, and you won't slip(滑) or fall.

       ●Be away from matches. Even a cigarette can easily start a fire. Don't use water to put out fires.

Use salt instead.

      ●Be careful with knives! Many people cut themselves in the kitchen. Never touch the broken bottles, doors or windows. Glass can also cause the most serious cuts.

      ●Don't keep poisons(毒药)in the kitchen.

      ●Never use electrical appliances(电器) in the shower. Dry the floor before you use them, or

electricity can hurt you!

      ●Keep children away from hot water and hot drinks. They can be dangerous. But adults often

forget it.

      ●Look through the peephole(门镜) when you hear the knock on the door. Don't let strangers in.

       In a word, we should learn to protect ourselves and stay away from danger.

根据短文内容,判断下列句子正误(T or F)

( )1. You must be careful when there is water on the floor.

(      )2. Salt can't be used for putting out fires.   

(      )3. It's not safe to use electrical appliances in the shower while the floor is wet.

(      )4. Water and drinks can be dangerous for both children and adults.

(      )5. Open the door at once when you hear someone knocking at the door

单项选择题 A1/A2型题