8/14/2019 Lecture Outlines Chapter 2
1/26
2007 Pearson Prentice Hall
This work is protected by United States copyright laws and is provided solely for the use
of instructors in teaching their courses and assessing student learning. Dissemination orsale of any part of this work (including on the World Wide Web) will destroy the integrity
of the work and is not permitted. The work and materials from it should never be made
available to students except by instructors using the accompanying text in their classes.
All recipients of this work are expected to abide by these restrictions and to honor the
intended pedagogical purposes and the needs of other instructors who rely on these
materials.
Lecture Outlines
Chapter 2
Physics, 3rd Edition
James S. Walker
8/14/2019 Lecture Outlines Chapter 2
2/26
Chapter 2
One-Dimensional Kinematics
8/14/2019 Lecture Outlines Chapter 2
3/26
Units of Chapter 2
Position, Distance, and Displacement
Average Speed and Velocity
Instantaneous Velocity
Acceleration
Motion with Constant Acceleration
Applications of the Equations of Motion
Freely Falling Objects
8/14/2019 Lecture Outlines Chapter 2
4/26
2-1 Position, Distance, and Displacement
Before describing motion, you must set up acoordinate system define an origin and a positive
direction.
8/14/2019 Lecture Outlines Chapter 2
5/26
2-1 Position, Distance, and Displacement
The distance is the total length of travel; if you drive
from your house to the grocery store and back, you
have covered a distance of 8.6 mi.
8/14/2019 Lecture Outlines Chapter 2
6/26
2-1 Position, Distance, and Displacement
Displacement is the change in position. If you drive
from your house to the grocery store and then to
your friends house, your displacement is 2.1 mi and
the distance you have traveled is 10.7 mi.
8/14/2019 Lecture Outlines Chapter 2
7/26
2-2 Average Speed and Velocity
The average speed is defined as the distancetraveled divided by the time the trip took:
Average speed = distance / elapsed time
Is the average speed of the red car 40.0 mi/h, morethan 40.0 mi/h, or less than 40.0 mi/h?
8/14/2019 Lecture Outlines Chapter 2
8/26
2-2 Average Speed and Velocity
Average velocity = displacement / elapsed time
If you return to your starting point, your average
velocity is zero.
8/14/2019 Lecture Outlines Chapter 2
9/26
2-2 Average Speed and Velocity
Graphical Interpretation of Average Velocity
The same motion, plotted one-dimensionally
and as anx-tgraph:
8/14/2019 Lecture Outlines Chapter 2
10/26
2-3 Instantaneous Velocity
Definition:
(2-4)
This means that we evaluate the average velocity
over a shorter and shorter period of time; as that
time becomes infinitesimally small, we have the
instantaneous velocity.
8/14/2019 Lecture Outlines Chapter 2
11/26
2-3 Instantaneous Velocity
This plot shows the average velocity being
measured over shorter and shorter intervals. The
instantaneous velocity is tangent to the curve.
8/14/2019 Lecture Outlines Chapter 2
12/26
8/14/2019 Lecture Outlines Chapter 2
13/26
2-4 Acceleration
Average acceleration:
(2-5)
8/14/2019 Lecture Outlines Chapter 2
14/26
2-4 Acceleration
Graphical Interpretation of Average and
Instantaneous Acceleration:
8/14/2019 Lecture Outlines Chapter 2
15/26
2-4 Acceleration
Acceleration (increasing speed) and deceleration
(decreasing speed) should not be confused with thedirections of velocity and acceleration:
8/14/2019 Lecture Outlines Chapter 2
16/26
2-5 Motion with Constant Acceleration
If the acceleration is constant, the velocity changes
linearly:
(2-7)
Average velocity:
8/14/2019 Lecture Outlines Chapter 2
17/26
2-5 Motion with Constant Acceleration
Average velocity:
(2-9)
Position as a function of time:
(2-10)
(2-11)
Velocity as a function of position:
(2-12)
8/14/2019 Lecture Outlines Chapter 2
18/26
8/14/2019 Lecture Outlines Chapter 2
19/26
2-5 Motion with Constant Acceleration
8/14/2019 Lecture Outlines Chapter 2
20/26
2-6 Applications of the Equations of Motion
Hit the Brakes!
8/14/2019 Lecture Outlines Chapter 2
21/26
2-7 Freely Falling Objects
Free fall is the motion of an object subject only to
the influence of gravity. The acceleration due togravity is a constant, g.
2 F l F lli Obj
8/14/2019 Lecture Outlines Chapter 2
22/26
2-7 Freely Falling Objects
An object falling in air is subject to air resistance
(and therefore is not freely falling).
2 7 F l F lli Obj t
8/14/2019 Lecture Outlines Chapter 2
23/26
2-7 Freely Falling Objects
Free fall from rest:
2 7 F l F lli Obj t
8/14/2019 Lecture Outlines Chapter 2
24/26
2-7 Freely Falling Objects
Trajectory of a projectile:
S f Ch t 2
8/14/2019 Lecture Outlines Chapter 2
25/26
Summary of Chapter 2
Distance: total length of travel
Displacement: change in position
Average speed: distance / time
Average velocity: displacement / time
Instantaneous velocity: average velocity measured
over an infinitesimally small time
S f Ch t 2
8/14/2019 Lecture Outlines Chapter 2
26/26
Summary of Chapter 2
Instantaneous acceleration: average acceleration
measured over an infinitesimally small time
Average acceleration: change in velocity divided
by change in time
Deceleration: velocity and acceleration haveopposite signs
Constant acceleration: equations of motion relate
position, velocity, acceleration, and time
Freely falling objects: constant acceleration
g= 9.81 m/s2