Download Notes: Position, Displacement, Speed, and Velocity

Name: _________________________
670
Section:_____
Date:____/____/____
Notes: Position, Displacement, Speed, and Velocity
Position:


being able to describe an object’s location is important when things start to move
object’s can have positive or negative positions
o
____________ position if it is to the right of or above
an object has a
the origin (zero point)
____________
o

an object has a
position if it is to the left of or below the
origin (zero point)
if an object’s position is changing, the object is in motion
Distance & Displacement


Definitions:
o Distance: measurement of the actual path traveled
o Displacement: the straight-line distance between 2 points with direction
A mouse ran in a curved path from his mouse hole to the cheese.
Path A = 4 meters
N
Path B = 2 meters
W
E
S
o
o
o
o
o
____________
Which path shows the distance the mouse traveled? ____________
What is the mouse’s displacement? ____________
What distance does the mouse travel? ____________
Which path shows the mouse’s displacement?
After running 4 meters from his hole to the cheese, the mouse returned to his
hole (using the same path).
 What total distance did the mouse run?
____________
 What is the mouse’s total displacement?
Standard(s): 1.1, 1.2
TA: _____________
____________
Independence Level: __________%
Assistance, coaching, prompting: __________________________________________________
Vectors and Scalars:

You may have noticed that direction sometimes matters.
o What are two quantities we have learned about so far where direction matters?




____________
____________

Vector: If direction matters, we say that the quantity is a vector.
Scalar: If direction doesn’t matter, we say that the quantity is a scalar.
Fill in examples of vectors and scalars in the following chart:
Direction
Matters
Measurable
Quantities
Direction Doesn’t
Matter
Scalar
Vector
Examples:
Examples:
Speed:


If you change positions, it takes time to get to your new position
If you care about both the distance traveled and the time it takes, you are concerned
with speed.
o Speed: distance traveled per unit of time

Speed tells us how

____________ an object is moving
The units of speed are ____________ /____________
o the unit is often written with symbols instead: __ /__

The definition equation for speed is
Speed =

Distance
Time
How do you know what speed you are moving at when you are in a car?


Instantaneous Speed: the speed at any instant (in time)
o What tool can you use to determine the instantaneous speed of a moving car?
_____________________

Constant Speed: if the speed of the moving object does not change, we say that it is
traveling at a constant speed

If you drive from Newton to Providence, RI, would you travel at a constant speed?
Explain.


Average Speed: total distance traveled divided by the time it takes to travel that distance
The definition equation for speed is
average speed =

total distance
time
Sample Problem:
o If you traveled 100 m in 50 seconds, what was your average speed?
s=?
d = 100 m
t = 50 s

s =
d
t
s =
100 m
 2
50 s
m
s
The average speed is 2 m/s
o

If you 
had average speed of 2 m/s, did you have to travel at 2 m/s for the entire
50 seconds? Explain.

Velocity: speed and direction
o Sometimes, we care about both how fast you are traveling and what direction
you are traveling.
o An example of velocity would be 25 m/s West
 the speed is 25 m/s
 the direction is West
 both of these are needed to describe velocity


What two tools can be used to determine the velocity of a car?
1.
_____________________
2.
_____________________
Changing Velocity: to change velocity, you could:
1. speed up
2. slow down
3. change direction


What three tools can be used to change the velocity of a car?
1.
_____________________
2.
_____________________
3.
_____________________
Write “speed” and “velocity” in the correct column(s) in the vector/scalar table below:
vectors
scalars


displacement
force


distance
time

____________
____________

____________
____________


Variables, units, and symbols:
Quantity
Symbol
s
d
t
v
Quantity
Term
speed
distance
time
velocity
Unit
meters/second
meter
second
meters/second
Unit
Symbol
m/s
m
s
m/s