Question 14 Marks
A $4.0\ kg$ block is suspended from the ceiling of an elevator through a, string having a linear mass density of $19.2 \times 10^{-3}kg/m.$ 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 $2.0m/s^2$. Take $g = 10m/s^2.$
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, $\text{v}=\sqrt{\Big(\frac{\text{T}}{\text{m}}\Big)}=50\text{m/s}$
View full question & 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, $\text{v}=\sqrt{\Big(\frac{\text{T}}{\text{m}}\Big)}=50\text{m/s}$