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The position vector for an electron is \(\vec{r}=(6.0 \mathrm{~m}) \hat{\mathrm{i}}-\) \((4.0 \mathrm{~m}) \hat{\mathrm{j}}+(3.0 \mathrm{~m}) \hat{\mathrm{k}}\). (a) Find the magnitude of \(\vec{r}\). (b) Sketch the vector on a right-handed coordinate system.

Short Answer

Expert verified
(a) Magnitude of \(\vec{r}\) is approximately 7.810 meters. (b) Sketch \(\vec{r}\) from (0,0,0) to (6, -4, 3).

Step by step solution

01

Understanding the Problem

The problem asks us to find two things related to the position vector \(\vec{r}\) of an electron: its magnitude and a sketch of the vector in a 3D coordinate system. \(\vec{r}\) is given as \((6.0 \mathrm{~m}) \hat{\mathrm{i}} - (4.0 \mathrm{~m}) \hat{\mathrm{j}} + (3.0 \mathrm{~m}) \hat{\mathrm{k}}\).
02

Formula for Magnitude of a Vector

To find the magnitude of a vector \(\vec{v} = a \hat{\mathrm{i}} + b \hat{\mathrm{j}} + c \hat{\mathrm{k}}\), we use the formula:\[ |\vec{v}| = \sqrt{a^2 + b^2 + c^2} \]
03

Substitute Values into the Formula

Substitute the components of \(\vec{r}\) into the magnitude formula. Here, \(a = 6.0\), \(b = -4.0\), and \(c = 3.0\).\[ |\vec{r}| = \sqrt{(6.0)^2 + (-4.0)^2 + (3.0)^2} \]
04

Calculate the Squares

Calculate the squares of the components:\(6.0\) squared is \(36.0\),\(-4.0\) squared is \(16.0\),\(3.0\) squared is \(9.0\).
05

Sum the Squares

Add the squares together:\[ 36.0 + 16.0 + 9.0 = 61.0 \]
06

Take the Square Root

Find the square root of the sum:\[ \sqrt{61.0} \approx 7.810 \] meters. This is the magnitude of \(\vec{r}\).
07

Sketching the Vector

To sketch the vector \(\vec{r}\) in a right-handed coordinate system, plot the point \((6.0, -4.0, 3.0)\). Begin from the origin, move 6 units along the x-axis (\(\hat{\mathrm{i}}\)), 4 units backward along the y-axis (\(\hat{\mathrm{j}}\)), and 3 units up along the z-axis (\(\hat{\mathrm{k}}\)). Join the origin to this point to represent the vector.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Position Vector
Imagine you're trying to pinpoint the exact location of something in space, like an electron. A position vector helps you do just that! It tells you where and in which direction an object is relative to a point called the origin. In the case of a 3D environment, you will typically see components like - \(\hat{\mathrm{i}}\) for the x-axis.- \(\hat{\mathrm{j}}\) for the y-axis.- \(\hat{\mathrm{k}}\) for the z-axis.
For our electron, the position vector is \(\vec{r}=(6.0 \mathrm{~m}) \hat{\mathrm{i}}-(4.0 \mathrm{~m}) \hat{\mathrm{j}}+(3.0 \mathrm{~m}) \hat{\mathrm{k}}\). This means we start at the origin, move 6 units along the \(\hat{\mathrm{i}}\) direction, 4 units backwards along \(\hat{\mathrm{j}}\), and 3 units up along \(\hat{\mathrm{k}}\).

Why is this helpful? Because it allows us to know precisely where the electron is, just like coordinates on a map. This vector is essential because it gives both the direction and the distance from the origin to the current position.
3D Coordinate System
When talking about location, a 3D coordinate system is like a magical grid. It helps us define where things are in space.Each position is described using three numbers, or coordinates, corresponding to the x, y, and z axes.

Here's a simple way to think about these axes:
  • The x-axis points left or right
  • The y-axis points forward or backward
  • The z-axis points up or down
These axes help us visualize where an object is located. For the vector \(\vec{r}=(6.0 \mathrm{~m}) \hat{\mathrm{i}}-(4.0 \mathrm{~m}) \hat{\mathrm{j}}+(3.0 \mathrm{~m}) \hat{\mathrm{k}}\), we're working in a 3D world. It allows us to understand movements and get a spatial sense of orientation. We use this system to calculate vector magnitudes, position vectors, and even forecast paths!
Being comfortable with a 3D coordinate system is very useful in a variety of fields, from engineering to video game design. Just always remember it all starts from the origin point, typically (0,0,0).
Right-Handed Coordinate System
The right-handed coordinate system is a common way to set up the 3D coordinate system.Why "right-handed"? Because if you curl the fingers of your right hand from the x-axis direction towards the y-axis, your thumb will naturally point along the z-axis.

This system is especially popular in physics, engineering, and computer graphics. It helps ensure that everyone is speaking the same language when it comes to orientation in space. This consistency is important because it defines positive and negative directions as well as rotations.
To locate the vector \(\vec{r}=(6.0 \mathrm{~m}) \hat{\mathrm{i}}-(4.0 \mathrm{~m}) \hat{\mathrm{j}}+(3.0 \mathrm{~m}) \hat{\mathrm{k}}\), we follow these simple steps:
  • Start at the origin
  • Move 6 units in the positive x-direction, aligning with your thumb
  • Move -4 units in the y-direction, curling fingers from x towards y
  • Move 3 units up in the z-direction
With the right-handed system, visualizing and drawing vectors becomes intuitive and less prone to error. Understanding this system helps simplify calculations and improve spatial reasoning. This makes it easier to work on problems involving rotations and orientations in space.

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