Question

一列簡(jiǎn)諧橫波沿x軸傳播，t=0時(shí)刻的波形如圖所示．則從圖中可以看出（　�。�

A．這列波的波長(zhǎng)為5m

B．波中的每個(gè)質(zhì)點(diǎn)的振動(dòng)周期為4s

C．若已知波沿x軸正向傳播，則此時(shí)質(zhì)點(diǎn)a向下振動(dòng)

D．若已知質(zhì)點(diǎn)b此時(shí)向上振動(dòng)，則波是沿x軸負(fù)向傳播的

Answer 1

A、由波的圖象讀出波長(zhǎng)為4m．故A錯(cuò)誤．
    B、波速不知，周期無(wú)法算出．故B錯(cuò)誤
    C、若波沿x軸正向傳播，a點(diǎn)比x=2m的質(zhì)點(diǎn)振動(dòng)遲，則a向下振動(dòng)．故C正確．
    D、若質(zhì)點(diǎn)b向上振動(dòng)，則x=4m質(zhì)點(diǎn)比b質(zhì)點(diǎn)振動(dòng)早，波應(yīng)沿x軸正向傳播，故D錯(cuò)誤
故選C．