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Wave Motion and Waves on a String — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsWave Motion and Waves on a String4 Marks
Question
A 4.0kg block is suspended from the ceiling of an elevator through a, string having a linear mass density of 19.2 × 10-3kg/m. 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 2.0m/s2. Take g = 10m/s2.
✓

Answer

$\text{m}=19.2\times10^{-3}\text{kg/m}$

From the freebody diagram,

$\text{T}-4\text{g}-4\text{a}=0$

$\Rightarrow\text{T}=4(\text{a}+\text{g})=48\text{N}$

Wave speed, $\text{v}=\sqrt{\Big(\frac{\text{T}}{\text{m}}\Big)}=50\text{m/s}$

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