Chapter 3: Problem 80
The position vector for a particle is \(\mathbf{r}(t)=t \mathbf{i}+t^{2} \mathbf{j}+t^{3} \mathbf{k}\). The graph is shown here: Find the velocity vector at any time.
Short Answer
Expert verified
Velocity vector \( \mathbf{v}(t) = 1 \mathbf{i} + 2t \mathbf{j} + 3t^2 \mathbf{k} \).
Step by step solution
01
Understanding the Position Vector
The position vector is given as \( \mathbf{r}(t) = t \mathbf{i} + t^2 \mathbf{j} + t^3 \mathbf{k} \). This vector describes the particle's position in 3D space as a function of time \( t \). The components are \( t \mathbf{i} \), \( t^2 \mathbf{j} \), and \( t^3 \mathbf{k} \).
02
Differentiating the Position Vector
To find the velocity vector, we differentiate the position vector \( \mathbf{r}(t) \) with respect to time \( t \). This is because velocity is the rate of change of position with respect to time.
03
Derivative of the First Component
The derivative of \( t \) with respect to \( t \) is 1. So, the first component of the velocity vector is \( \frac{d}{dt}(t) = 1 \).
04
Derivative of the Second Component
The derivative of \( t^2 \) with respect to \( t \) is \( 2t \). So, the second component of the velocity vector is \( \frac{d}{dt}(t^2) = 2t \).
05
Derivative of the Third Component
The derivative of \( t^3 \) with respect to \( t \) is \( 3t^2 \). So, the third component of the velocity vector is \( \frac{d}{dt}(t^3) = 3t^2 \).
06
Constructing the Velocity Vector
Combining all the differentiated components, the velocity vector \( \mathbf{v}(t) \) is \( \mathbf{v}(t) = 1 \mathbf{i} + 2t \mathbf{j} + 3t^2 \mathbf{k} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Position Vector
In the world of vector calculus, the **position vector** is an essential concept. It provides information about the location of a particle in space over time. Given by the function \( \mathbf{r}(t) = t \mathbf{i} + t^2 \mathbf{j} + t^3 \mathbf{k} \), this vector has several components:
- \( t \mathbf{i} \): Represents movement along the x-axis.
- \( t^2 \mathbf{j} \): Illustrates the movement along the y-axis.
- \( t^3 \mathbf{k} \): Describes the movement along the z-axis.
Velocity Vector
The **velocity vector** is crucial as it describes how the position of the particle changes over time. Derived from differentiating the position vector, it gives us a snapshot of the particle's direction and speed at any given moment. The velocity vector is calculated as:
- First component: Derivative of \( t \) is 1. Resulting in velocity \( \, \mathbf{i} \).
- Second component: Derivative of \( t^2 \) is \( 2t \). Resulting in velocity \( 2t \mathbf{j} \).
- Third component: Derivative of \( t^3 \) is \( 3t^2 \). Resulting in velocity \( 3t^2 \mathbf{k} \).
Differentiation
**Differentiation** is a fundamental tool in calculus and is essential for finding rates of change. In the context of vector calculus:
- It helps in determining velocities from position vectors.
- It allows us to understand how each component of the position vector changes with respect to time.
- The derivative of \( t^n \) is \( nt^{n-1} \).
3D Space
Operating in **3D space** introduces a whole new layer of complexity and excitement. Unlike the 2D plane, every point in 3D is defined by three coordinates: \( x \), \( y \), and \( z \). This is depicted by our position vector in the form \( \mathbf{r}(t) = t \mathbf{i} + t^2 \mathbf{j} + t^3 \mathbf{k} \).
- \( \mathbf{i} \) represents the x-axis.
- \( \mathbf{j} \) denotes the y-axis.
- \( \mathbf{k} \) indicates the z-axis.