A string of length 20 cm and linear mass density `0.4 g//cm ` is fixed at both ends and is kept under a tension of 16 N. A wave pulse is produced at t=0 near an end as shown in figure which travels towards the other end. (a) When will the string have the shape shown in the figure again? (b) Sketch the shape of the string at a time half of that found in part (a).

Answer

A, B

Explanation

a. Velcity of the wave
`v=sqrt((T/m))`
`sqrt((16x1^5)/0.4)`
`=2000cm/sec`
`:. Time taken to reach to the other end
`=20/2000=0.01sec`
Time taken to see the pulse again in the origiN/Al position
`=0.01xx2=0.02sec`
b. At t=0.01s, then will be a trough at the right end as it is reflected.