Chapter 1: Problem 25
If \(f(t)=t^{2}\) then \(v(t)=2 t .\) Does the speeded-up function \(f(4 t)\) have velocity \(v(4 t)\) or \(4 v(t)\) or \(4 v(4 t) ?\)
Short Answer
Expert verified
Speeded-up function has velocity 32t.
Step by step solution
01
Understanding Function Composition
The problem requires determining the velocity of the speeded-up function \(f(4t)\). First, understand that speeded-up means substituting \(4t\) into the original function \(f(t) = t^2\), so the new function becomes \(f(4t) = (4t)^2 = 16t^2\).
02
Calculating the Derivative for Velocity
The velocity of a function \(g(t)\) is the derivative of \(g(t)\) with respect to \(t\). We know \(v(t) = 2t\) for \(f(t) = t^2\). For the speeded-up function \(f(4t) = 16t^2\), find the derivative: \(\frac{d}{dt}[16t^2] = 32t\).
03
Comparing Velocity Expressions
Now, compare the calculated velocity \(32t\) with the provided options. We have \(v(4t) = 2(4t) = 8t\) and \(4v(t) = 8t\), and \(4v(4t) = 16t\). Note that \(32t\) matches none directly, but if multiplied by 4, it can resemble one of the options, suggesting both scaling and dependency on \(t\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Derivatives
The concept of a derivative is a cornerstone in calculus. It measures how a function changes as its input changes. In simpler terms, a derivative tells us the rate of change of a function. For example:
- If we have a function that represents the position of a car over time, the derivative of that function will represent the speed of the car at any given moment.
- Mathematically, the derivative of a function at a point is the slope of the tangent line at that point.
Relating Velocity to Derivatives
Velocity is a term that describes the speed of an object in a specific direction. It is essentially the derivative of a position function in physics. When you have a function that represents position, like \(f(t) = t^2\), its derivative \(v(t) = 2t\) gives the velocity:
- Velocity tells us how quickly and in what direction an object's position is changing over time.
- In the context of the exercise, the velocity for \(f(4t)\) was found through derivative calculations.
Using Substitution in Calculus
Substitution is a technique used to simplify calculus problems by replacing one variable with another. In function composition, substitution involves inserting a function into another function:
- This is particularly useful in problems where a function needs to be evaluated at a new expression of the input variable.
- For the given problem, we replaced \(t\) with \(4t\) in the function \(f(t) = t^2\) to get \(f(4t) = 16t^2\).
Problem Solving in Calculus
Calculus problem-solving often requires systematic steps and a good understanding of concepts like derivatives and substitution. Here’s how to approach these problems effectively:
- Identify known elements: What is given in the problem? In this case, we know \(f(t) = t^2\) and its derivative velocity \(v(t) = 2t\).
- Look for what is unknown: Determine what you need to find, like the new velocity for \(f(4t)\).
- Apply relevant calculus concepts: Use derivatives and substitution appropriately to find the solution.
- Compare results: After solving, match your answer against provided options to verify accuracy.