Using a Scale Drawing to Add Vectors
Using arrows to represent vectors is convenient especially when we want to start to adding vectors up Look at the vector calculations below
Lets get moving
Very straightforward when the vectors are in the same plane; That is purely:
EAST and WEST or NORTH and SOUTH
When we add vectors that are say NORTH with EAST we must use a scale drawing!!!
1
2
When you want to make a nice scale drawing follow these steps
Ex #1: Add the following vectors Vector 1: 30 km North
Vector 2: 50 km East
Step 1
Choose a scale and indicate it on a sheet of paper (the best choice of scale is one which will result in a diagram which is as large as possible within reason, yet fits on the sheet of paper). You must also indicate which way is North on your page
N
In this case 1 cm = 5 km
E
W
S
Step 2
Pick a starting location and draw the first vector to scale in the indicated direction. Label the magnitude and direction of the scale on the diagram 3
Step 3 Starting from where the head of the first vector ends, draw the second vector to scale in the indicated direction. Label the magnitude and 1 cm = 5 km
direction of the vector on the diagram
N
N
Start
N
our tools!
4
Step 4
If you have correctly placed all of your vectors then
Draw the resultant from the tail of the first vector to the head of the last vector. Label this vector as "Resultant" or simply "R." Using a ruler, measure the length of the resultant and determine its magnitude by converting to real units using the scale In this case the resultant was 11.7 cm which is about 58.5 km
Step 6
Measure the angle of the vector relative to where you started from and name it appropriatley
In this case the [59 E of N]
5
Add Using a scale drawing
Vector 1: 60 km South
Vector 2: 30 km [30 N of E]
N
N
Start
N
6
Vector 1: 15 m/s [30 N of E]
Vector 2: 50 m/s [20 S of E]
Vector 3: 35 m/s W
N
N
N
Start
N
7
Lets try this before I give you an assignment
A Penguin marches according to the information below
Phase 1: 30 km [110o] in 3 hours
Phase 2: 25 km [230o ] in 150 minutes
a) Draw a scale drawing of the "marching"
b) Determine the distance and displacement of the penguins
c) Calculate the average speed and avaerage velocity of the penguins
N
N
1 cm is 5 km
N
start
8
Here comes the assignment!
Tackle the questions on Page 90
Use scale drawings when asked to add
2, 6, 9, 11
9
Attachments
vector assignment.doc