Chapter 2: Problem 31
Find the indicated derivative. $$V^{\prime}(r), \text { where } V=\pi r^{3}$$
Short Answer
Expert verified
The derivative is \( V'(r) = 3\pi r^2 \).
Step by step solution
01
Identify the Function
The function given is the volume function, where \( V = \pi r^3 \). This indicates that \( V \) is a function of \( r \).
02
Apply the Power Rule for Derivatives
The power rule for derivatives states that if you have a function of the form \( r^n \), its derivative is \( n \times r^{n-1} \). For our function \( V = \pi r^3 \), \( n = 3 \). Thus, the derivative of \( r^3 \) is \( 3r^2 \).
03
Multiply by the Constant Coefficient
Since \( \pi \) is a constant multiplier in the original function \( V = \pi r^3 \), we multiply the derivative \( 3r^2 \) by \( \pi \). Therefore, \( V'(r) = 3\pi r^2 \).
04
State the Derivative
The derivative of the volume function \( V \) with respect to \( r \) is \( V'(r) = 3 \pi r^2 \). This tells us how the volume changes as the radius \( r \) changes.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Power Rule
The power rule is a fundamental concept in calculus used to find derivatives of functions with exponents. When you have a function like \( r^n \), the power rule helps us determine the derivative efficiently. The rule states: take the exponent \( n \) and multiply it by the base raised to the power of \( n-1 \).
For example:
For example:
- If \( f(r) = r^3 \), then the derivative \( f'(r) \) is \( 3r^2 \).
Volume Function
In calculus, a volume function represents how the volume of a geometric shape changes with respect to a variable. For a sphere or similar objects, it could depend on the radius. In the exercise given, the volume function is \( V = \pi r^3 \).
Here,
Here,
- \( \pi \) is a constant, which represents the mathematical constant pi.
- \( r \) is the radius of the sphere.
Constant Multiplier
A constant multiplier in a function is a coefficient that remains unchanged regardless of the variable. When taking the derivative of such a function, this constant simply multiplies the derivative of the variable component. For the given function \( V = \pi r^3 \), \( \pi \) is the constant multiplier.
- When differentiating, you first apply the power rule to \( r^3 \) to get \( 3r^2 \).
- Then, multiply this result by the constant \( \pi \), giving us \( 3\pi r^2 \).
Function of a Variable
A function of a variable expresses how one quantity, dependent on another, changes as that variable changes. In our exercise, the volume \( V \) depends on the radius \( r \), which means \( V \) is a function of \( r \). This relationship is essential because it helps to understand how a change in radius impacts the volume.
When dealing with functions of a variable, consider:
When dealing with functions of a variable, consider:
- The independent variable (\( r \)) is the input.
- The dependent variable (\( V \)) is what changes according to the input.