A 4.0 kg block is suspended from the ceiling of an elevator through a string having a linear mass desity of `19.2xx10^-3 kgm^-1`. Find the speed (with respect to the string) with which a wave pulse can proceed on the string if the elavator accelerates up at the rate of `2.0ms^-2. Take g=10 ms^-2`.

Answer

A

Explanation

m=19.2xx10^-3kg/m`
From the freebody diagram,
`T-4g-4a=0`
`rarr T=4(a+g)`
`=4(2+10)=48N`

` Wave speed v=sqrt((T/m))`
`=(48/(19.2xx10^3))`
`=sqrt((2.5xx10^I-3))=50m/s`