Math Problem Statement

The following table shows the wind chill C(T,w) (in °F ) as a function of the air temperature T (in °F ) and the wind speed w (in miles per hour)

according to the current National Weather Service model.

There are three ways to estimate a partial derivative from a table of values, the forward difference quotient (for example,

fx(a,b)~~f(a+h,b)-f(a,b)h with h>0 ), the backward difference quotient (for example, fx(a,b)~~f(a,b)-f(a-h,b)h with h>0 ), and the

symmetric difference quotient (for example, fx(a,b)~~f(a+h,b)-f(a-h,b)2h with h>0 ). The symmetric difference quotient is just the average

of the forward and backward difference quotients.

The forward difference quotient approximation to CT(30,15) is

°F°F. The backward difference quotient approximation to

CT(30,15) is

°F°F. The symmetric difference quotient approximation to CT(30,15) is

°F°F.

The forward difference quotient approximation to Cw(30,15) is

°Fmph. The backward difference quotient approximation to

Cw(30,15) is

°Fmph. The symmetric difference quotient approximation to Cw(30,15) is

°Fmph.

The National Weather Service has also provided an empirical formula for approximating the wind chill. It states that

C(T,w)~~35.74+0.6215T+w0.16(-35.75+0.4275T)

Based on this formula, CT(30,15)~~

°F°F and Cw(30,15)~~

°Fmph.

Solution

To address the partial derivatives for the wind chill function C(T,w)C(T, w), let's break down the problem into a few key steps.

Partial Derivatives:

  • CT(T,w)C_T(T, w) refers to the partial derivative of CC with respect to the temperature TT while keeping the wind speed ww constant.
  • Cw(T,w)C_w(T, w) refers to the partial derivative of CC with respect to the wind speed ww while keeping the temperature TT constant.

Estimating the Partial Derivatives Using the Difference Quotients:

For approximations, we use the following methods:

  1. Forward Difference Quotient:
    fT(a,b)f(a+h,b)f(a,b)hf_T(a, b) \approx \frac{f(a+h, b) - f(a, b)}{h} fw(a,b)f(a,b+h)f(a,b)hf_w(a, b) \approx \frac{f(a, b+h) - f(a, b)}{h}
  2. Backward Difference Quotient:
    fT(a,b)f(a,b)f(ah,b)hf_T(a, b) \approx \frac{f(a, b) - f(a-h, b)}{h} fw(a,b)f(a,b)f(a,bh)hf_w(a, b) \approx \frac{f(a, b) - f(a, b-h)}{h}
  3. Symmetric Difference Quotient:
    fT(a,b)f(a+h,b)f(ah,b)2hf_T(a, b) \approx \frac{f(a+h, b) - f(a-h, b)}{2h} fw(a,b)f(a,b+h)f(a,bh)2hf_w(a, b) \approx \frac{f(a, b+h) - f(a, b-h)}{2h}

Using the Formula for C(T,w)C(T, w):

The given formula for C(T,w)C(T, w) is: C(T,w)35.74+0.6215T+w0.16(35.75+0.4275T)C(T, w) \approx 35.74 + 0.6215T + w^{0.16} \left( -35.75 + 0.4275T \right) This formula will allow us to compute the analytical derivatives for CT(30,15)C_T(30, 15) and ( C_w(30,

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Math Problem Analysis

Mathematical Concepts

Partial Derivatives
Difference Quotients
Empirical Formulas
Wind Chill

Formulas

Forward Difference Quotient: f_T(a, b) ≈ (f(a+h, b) - f(a, b)) / h
Backward Difference Quotient: f_T(a, b) ≈ (f(a, b) - f(a-h, b)) / h
Symmetric Difference Quotient: f_T(a, b) ≈ (f(a+h, b) - f(a-h, b)) / (2h)
Wind Chill Formula: C(T, w) ≈ 35.74 + 0.6215T + w^0.16(-35.75 + 0.4275T)

Theorems

Difference Quotients Approximation

Suitable Grade Level

College Level