A string of length 40 cm and weighing 10 g is attached to a spring at one end and to a fixed wall at the other end. The spring has a spring constant of `160 N m^-1` and is stretched by 1.0 cm. If a wave pulse is produced on the string near the wall, how much time will it take to reach the spring ?

Explanation

L=40 cm, mass=10gm
………mass per unit length
`=10/40=1/4(gm/cm)`
`Spring costant=k=160N/m`
Deflection =x=1cm`
`=0.01m`
`rarr T=kx=160x0.01`
`=1.6N=6xx10^4 dyne`
Again `v=sqrt((T/m)0=sqrt(((16x10^4)/(1/4)))`
`=8xx10^2cm/s=800cm/s`
`:. time taken by the pulse to reach the spring. `t=40/800=1/20=0.05sec`