In the arrangement shown in figure, the string has a mass of 4.5 g. How much time will it take for a transverse disturbance produced at the floor to reach the pulley ? Take `g=10ms^-2`
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Answer

B

Explanation

Total length of string `=2+0.25=2.25m`
Mass per unit length
`m=(4.5xx10^-3)/2.25`
`=2xx10^-3kg/m`
`T=2g=20N`
`wave speed v=sqrt((T/m))`
`sqr((20/(2xx10^-3)))`
`=sqrt10^4`
`=10^2m/s=100m/s`

Time taken to reach the pulley,
`t=(s/v)`
`=2/100=0.02sec`.