the height of a cylinder is increasing at a rate of 2 inches per second, while the radius is decreasing at a…

the height of a cylinder is increasing at a rate of 2 inches per second, while the radius is decreasing at a rate of 4 inches per second. if the height is currently 50 inches, and the radius is 11 inches, then find the rate of change in the volume. round your answer to one decimal place. ( the formula for the volume of a cylinder is v = πr²h. ) the rate of change in the volume is □ in³/sec
Answer
Explanation:
Step1: Differentiate volume formula
The volume of a cylinder is $V = \pi r^{2}h$. Using the product - rule $\frac{d(uv)}{dt}=u\frac{dv}{dt}+v\frac{du}{dt}$, where $u = \pi r^{2}$ and $v = h$. So $\frac{dV}{dt}=\pi\left(2rh\frac{dr}{dt}+r^{2}\frac{dh}{dt}\right)$.
Step2: Substitute given values
We know that $\frac{dh}{dt}=2$ in/sec, $\frac{dr}{dt}=- 4$ in/sec, $h = 50$ in, and $r = 11$ in. Substitute these values into the formula for $\frac{dV}{dt}$: [ \begin{align*} \frac{dV}{dt}&=\pi\left[2\times11\times50\times(-4)+11^{2}\times2\right]\ &=\pi\left[ - 4400+242\right]\ &=\pi\times(-4158)\ &\approx - 13053.2 \end{align*} ]
Answer:
$-13053.2$