Holt Physics
Chapter 2
Section 1
Coordinate System—location of the
+y
of the variable, defines
of direction of travel
Usually, object is placed at origin at beginning
Object shown as dot of travel; thus, x0 and t0 are 0.
+x
-x
-y
Δ—Greek letter
, denotes a
in a quantity, always final - initial
Scalar—value that has
(speed=30 mph, mass=12 kg).
Vector—value that has
and
is a scalar quantity
(velocity = 30 mph East). Denoted by bold font or arrow

over variable. (v = 30 m/s East or v  30m / s East ) On graph, represented by an arrow showing direction and
magnitude (length of arrow).
𝑣⃑
Displacement—
Symbol: 𝑥⃑
Unit:
Distance—
quantity that defines both the
and
between two positions.
in a specified direction
quantity that is the length of the path traveled. Flash animation difference between
Symbol: x
Unit:
Velocity—
of a graph of
quantity denoting
in distance during a time interval. Magnitude is the slope
versus time. Unit is
in a specified direction
Symbol: 𝑣⃑
Unit: m/s in a given direction
Average Velocity—
quantity that tells how fast an object is moving. Unit is
in a specified
direction.
𝑥1 − 𝑥0
𝑣⃑ =
𝑡1 − 𝑡0
Average Speed—quantity denoting the distance traveled divided by the time interval. Unit is
Instantaneous Velocity—
instant. Unit is
quantity denoting the displacement divided by the time at any particular
Displacement-Velocity Relationship—displacement can be calculated if the
is known. Unit is
and the
𝑥
⃑⃑⃑⃑1 = ⃑⃑⃑⃑⃑
𝑥0 + 𝑣⃑𝑡
Rearranging, ⃑⃑⃑⃑
𝑥1 = 𝑣⃑𝑡 + ⃑⃑⃑⃑⃑
𝑥0
Recognize this is equation for a straight line: y = mx + b
x1
𝑥⃑,
m
slope =
t1
t, s
Complete Practice A on p 44, #1, 3, & 5
The four starred equations on reference sheets are all you need to solve any motion problem:
∆𝑥
𝑥−𝑥
Definition of velocity:
𝑣 = ∆𝑡 = 𝑡−𝑡 0 ; 𝑥 = 𝑥0 + 𝑣𝑡
∆𝑣
0
Definition of acceleration:
𝑎=
Displacement equation:
Velocity squared equation:
𝑥 = 𝑥0 + 𝑣0 𝑡 + 2 𝑎𝑡 2 (use when you have or need time)
𝑣 2 = 𝑣02 + 2𝑎(𝑥 − 𝑥0 ) (use when you don’t have time)
∆𝑡
=
𝑣−𝑣0
𝑡−𝑡0
; 𝑣 = 𝑣0 + 𝑎𝑡
1
Section 2:
Objectives:
1. Describe motion in terms of changing velocity.
2. Compare graphical representations of accelerated and nonaccelerated motions.
3. Apply kinematic equations to calculate distance, time, or velocity under conditions of constant
acceleration.
Acceleration—
quantity that is the rate of
of a graph of velocity versus time.
Symbol: 𝑎⃑
Unit: m/s2 in a specified direction
Average Acceleration—
𝑎=
⃑⃑
∆𝑣
∆𝑡
=
with respect to
. Magnitude is the
quantity denoting the change in average velocity per unit time
⃑⃑⃑⃑⃑−𝑣
𝑣
1 ⃑⃑⃑⃑⃑
0
𝑡1 −𝑡0
a1
𝑣
m/s
Slope _,
↑, acceleration _
slope = acceleration
a0 t0
t1
t, s
______= 0, velocity
, acceleration = __
Slope __ 0, velocity ↓, acceleration ____
Displacement depends on initial
,
and
1
𝑥 = 𝑥0 + 𝑣0 𝑡 + 𝑎𝑡 2
2
1
If object starts at origin, x0=0, and a is constant, 𝑥 = 𝑥0 + 𝑣0 𝑡 + 2 𝑎𝑡 2
0
.
Practice Problems C, p 53, #1 & 3
Practice Problems D, p 55, #1 & 3
Practice Problems E, p 58, #1, 3, & 5
Section 3 Falling Objects
Free fall: object falls with acceleration due to gravity only cause of motion
g ≡ acceleration due to gravity, 9.81 m/s2
Practice Problems F, p 64, #1 & 3