题干

振动周期为T,振幅为A,位于x=0点的被波源从平衡位置沿y轴正向开始做简谐运动,该波源产生的一维简谐横波沿x轴正向传播,波速为v,传播过程中无能量损失,一段时间后,该振动传播至某质点p,关于质点p振动的说法正确的是(   )

A:振幅一定为A

B:周期一定为T

C:速度的最大值一定为v

D:开始振动的方向沿y轴向上或向下取决于他离波源的距离

E:若p点与波源距离s=vT,则质点p的位移与波源的相同

上一题 下一题 0.0难度 选择题 更新时间:2020-03-01 11:17:55

答案(点此获取答案解析)

A,B,E

同类题5

补全短文。根据短文内容,从短文后的A-F选项中,选出5个适当的选项补全短文。

Try to help your dog relax

    It's a Saturday morning. You rush through breakfast, walk the dog, and then get to soccer practice on time. A few hours later, you return home, only to find that the dog has made your bedroom untidy.  ____ Your favorite sports shoes are in poor condition.

    Before you get angry, stop and think. Your dog wasn't misbehaving (行为不端) just for the fun of it. ____ Some dogs just feel nervous when left alone. It's called separation anxiety (分离焦虑).

    Think of it this way: Dogs can't ask where you're going or when you'll be back. They can't call you on the phone. ____ Since you're not there, they need to find you. Dogs may suddenly develop separation anxiety. But with practice and patience (耐心), you can teach your dog to be comfortable being left alone.

    Put on your jacket, and then sit back down. Open and close the door, and then sit down. After a while, walk out the door for 10 seconds, then 20, then a minute and so on. ____

    Besides, you can also try the following ways:

    Teach your dog a word or action that you use every time you leave, which tells your dog you'll be back.

    Help comfort (安慰) your dog by leaving a piece of clothing that smells like you.

    Before you leave, give your dog a toy. ____ 

A. Your clothes are on the floor.

B. It will keep him / her busy while you're away.

C. And he / she wasn't punishing you for leaving.

D. All they know is that they want to be with you.

E. Little by little your dog will learn that when you leave, you will return.

F. You can help your dog by offering him / her some food.