# Describing Motion ```Describing Motion
Picturing Motion
Motion Diagrams
– A series of images
of a moving object
Particle Model
Particle Model
– Replacing an object by a single point.
– Example  Ticker Timer Lab
Vectors and Scalars
A quantity that has only magnitude
is referred to as a scalar quantity
A quantity that has magnitude and
direction is referred to as a vector
quantity
– The arrow head indicates direction,
while the length of the arrow indicates
magnitude
Vector Diagrams
Interpret the motion of the following
diagram.
velocity vector look like? Draw it.
Time Intervals and Displacement
Displacement is the change in
position of an object (defines the
distance and direction between two
positions)
– Therefore d =df - di
Time interval is the difference
between ti and tf
– Therefore t =tf – ti
Velocity and Acceleration
Average Velocity
– Simply the slope of a Position vs. Time
Graph
V = d / t = (df – di) / (tf – ti)
Average Acceleration
– Simply the slope of a Velocity vs. Time
Graph
a= v / t = (vf – vi) / (tf – ti)
```