What is motion? How do you know if
something is “in motion?”
Motion is the changing distance
between two objects.
You can tell if something is “in motion”
based on a reference point.
Reference point: A place or object used
for comparison to determine if something
is in motion.
Are we moving right now? Yes? No?
How do you know?
What is your reference point?
**Technically, we are doing both moving
AND not moving depending on your
What is speed?
How do you know what “speed” you are
Is speed fast or slow? Or both?
Speed is the amount of distance an
object travels in any given amount of
We calculate speed like this:
Speed = Distance / Time
Average speed is just:
total distance / total time
What is velocity?
Is velocity the same thing as speed?
How do I know what an objects velocity
Velocity is speed with direction.
When dispatch contacts a police officer
to let them know where a suspect
is, they will give them a velocity: “the
perpetrator is on walnut st. traveling at
What else do we use velocity to
Change in velocity can be due to two
1. Change in speed
2. Change in direction
(it can be one or both)
What is acceleration?
What does it mean to accelerate?
What is the opposite of accelerate?
Acceleration is the rate at which velocity
changes with time.
If velocity requires both speed and
direction, then acceleration also
requires both speed and direction.
Therefore… acceleration refers to
increasing speed, decreasing speed or
Increasing speed: When an objects
speed increases, it is accelerating.
Decreasing speed: When an objects
speed decreases, it is deccelerating or
has negative acceleration.
Changing direction: If the direction
changes so does the acceleration- even
if the speed stays the same!!!
Calculating acceleration: you must figure
out the change in velocity per unit time.
Acceleration= Final velocity - Initial Velocity
The units used for Acceleration are meters
per second per second or m/s2