Question

如圖所示，實線為一列簡諧波在t=0時刻的波形，虛線表示經過△t=0.2s后它的波形圖象，已知T＜△t＜2T（T表示周期），則這列波傳播速度的可能值v=______；這列波的頻率可能值f=______．

Answer 1

由圖線可直接讀出波長λ=0.04m．
因為T＜△t＜2T
所以當波向右傳播時，0.2s=

5

4

T，周期T=

4

25

s，則f=

1

T

=

25

4

=6.25Hz，v=

λ

T

=

0.04

4 25

=0.25m/s
當波向左傳播時，0.2s=

7

4

T，周期T=

4

35

s，則f=

1

T

=

35

4

=8.75Hz，v=

λ

T

=

0.04

4 35

=0.35m/s
故答案為：0.25m/s，0.35m/s；6.25Hz，8.75Hz