A 40 kg block is suspended from the ceiling of an elevator through a string having a linear mass density of 192 × 10−3 kg m−1. Find the speed (with respect to the string) with which a wave pulse can proceed on the string if the elevator accelerates up at the rate of 20 m s−2. Take g = 10 m s−2.
50 m s−1
If we observe this from the frame of string, then we are going to measure an increase in mass due to pseudo force. This will increase the tension on the string.

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The mass density is 192 × 10−3 kg m−1
So, the speed will be,

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