The problem consists of four independent questions: d) Newton's Law of Cooling: The temperature of a cold drink is initially $3^\circ C$. After 30 minutes in a $15^\circ C$ room, the temperature increases to $10^\circ C$. We need to find a formula for the temperature of the cold drink after $t$ hours, and determine when the temperature will be $14^\circ C$. a) Function Analysis: Given a function $f: \{1, 2, 3\} \rightarrow \{0, 4\}$ such that $f(1) = 0$, $f(2) = 4$, and $f(3) = 4$, we need to sketch the graph of the function, find where $f$ has a local minimum value, find where $f$ has a local minimum value but not a global minimum, and find where $f$ has a global maximum value. b) Definite Integral: Given that $f$ is continuous on $R$ and $\int_0^1 f(x) dx = 3$, we need to find $\int_\pi^{\frac{5\pi}{4}} \cos(2x) f(\sin(2x)) dx$. c) Fundamental Theorem of Calculus: Given $f(x) = \int_{x^2}^{2025} (e^{y^2+1}) dy$, we need to find $f'(x)$ using the Fundamental Theorem of Calculus part 1 and then find $f'(1)$.
AnalysisDifferential EquationsNewton's Law of CoolingFunction AnalysisDefinite IntegralFundamental Theorem of CalculusCalculus
2025/6/19
1. Problem Description
The problem consists of four independent questions:
d) Newton's Law of Cooling: The temperature of a cold drink is initially . After 30 minutes in a room, the temperature increases to . We need to find a formula for the temperature of the cold drink after hours, and determine when the temperature will be .
a) Function Analysis: Given a function such that , , and , we need to sketch the graph of the function, find where has a local minimum value, find where has a local minimum value but not a global minimum, and find where has a global maximum value.
b) Definite Integral: Given that is continuous on and , we need to find .
c) Fundamental Theorem of Calculus: Given , we need to find using the Fundamental Theorem of Calculus part 1 and then find .
2. Solution Steps
d) (i) Newton's Law of Cooling states that the rate of change of temperature is proportional to the difference between the object's temperature and the ambient temperature. Let be the temperature of the cold drink at time (in hours). Then
where is a constant. The solution to this differential equation is
where is the initial temperature. We are given that , so
.
We are also given that . Plugging this in, we get
Thus, .
(ii) We want to find such that . So,
hours.
To the nearest hour, hour.
a) (i) The graph consists of three points: , , and .
(ii) A local minimum occurs at because is less than .
(iii) A local minimum that is not a global minimum doesn't exist in this function, since the minimum at is the global minimum as well. Thus, the answer is None.
(iv) Global maximum occurs at and since are the largest function values.
b) Let . Then , so .
When , . When , .
.
c) By the Fundamental Theorem of Calculus,
.
Therefore, .
3. Final Answer
d) (i)
(ii) 1 hour
a) (i) Graph with points (1,0), (2,4), (3,4)
(ii)
(iii) None
(iv)
b)
c)