This document provides an overview of key concepts in kinematics including: - Position, distance, and displacement as scalar and vector quantities - Definitions of speed, velocity, and acceleration, including average and instantaneous measures - Examples are given to illustrate calculating displacement and velocity for objects moving in one and two dimensions

1. Chapter 2
Kinematics: Description of
Motion

2. Units of Chapter 2
Distance and Speed: Scalar Quantities
One-Dimensional Displacement and Velocity: Vector
Quantities
Acceleration
Kinematic Equations (Constant Acceleration)
Free Fall

3. Position, Distance, Displacement
Position: Location that is described by referencing one
object/person to another object/person.
Distance: Scalar quantity (magnitude only) that
describes the length of the path traveled from
beginning to end.

4. • A puppy runs 40 meters east and then does a
180 and runs 10 meters to the west, stops,
and runs 10 more meters to the west.
• What was the puppy’s distance?

5. Position, Distance, Displacement
Displacement is a vector quantity that represents the
distance from the starting point (initial, xo ) to the end
( final, x) AND includes a direction.

6. Back to the Puppy
What was the Puppy’s displacement?

7. Speed
Average speed is a scalar rate that is equal to the
distance traveled divided by the elapsed time:

8. Speed
At times an instantaneous speed is required. It is
the speed measured over a very short time span.
This is what a speedometer reads on your car or
a radar gun on a police car reads.

9. Vector
A vector is a line that has both
magnitude and direction.
Manipulating vectors means defining
a coordinate system, as shown in the
diagrams to the left.

10. Velocity
Velocity is the rate the displacement changes in
a unit of time. It is a vector quantity. Its unit is
m/s.

11. If the puppy travels for 20
seconds, what was its average
velocity?

12. Note
For motion in a straight line with no reversals, the
average speed and the average velocity are the
same.

13. If a Road Runner travels east 6
meters, and with a flying leap
changes direction heads north
for 8 meters, what was Road
Runner’s speed and velocity if
he covered the distance in 30
seconds?

14. Acceleration
Acceleration is the rate at which velocity changes.
© 2010 Pearson Education, Inc.

15. The units of acceleration are m/s/s or m/s2
It is a vector quantity