Ch 1 (Etkina) Notes Flashcards

1
Q

When describing motion, we need to focus on two important aspects: the … whose motion we are describing (the …) and the … who is doing the describing (the …)

A

object; object of interest; person; observer

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2
Q

Motion is a change in an object’s …. relative to a …. during a certain change in ….

A

position; given observer; time

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3
Q

Without identifying the observer, it is impossible to say whether the object of interest

A

moved

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4
Q

physicists say motion is …., meaning that the motion of any object of interest depends on the …. of the observer

A

relative; point of view

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5
Q

people intuitively use … as the object of reference- the object with respect to which they …

A

earth; describe motion

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6
Q

what we view as the object of reference influences how we

A

describe motion

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7
Q

specifying the observer before describing the motion of an object of an interest is an extremely important part of constructing what physicists call a

A

reference frame

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8
Q

a reference frame includes an …, a …. with a … for measuring …, and a … to measure …

A

object of reference; coordinate system; scale; distances; clock; time

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9
Q

if the object of reference is large and cannot be considered a point-like object, it is important to specify where on the object of reference the … of the coordinate system is placed

A

origin

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10
Q

(reference frame includes) an object of reference with a specific …. on it

A

point of reference

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11
Q

(reference frame includes) a coordinate system, which includes one or more …., and an …. located at the … it also includes a … for specifying … along the xes

A

coordinate axes; origin; point of reference; scale; distances

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12
Q

(reference frame includes) a clock which includes an … called … and a unit of measurement for specifying … and ….

A

origin in time; t=0; time; time intervals

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13
Q

one-dimensional/linear motion is a model of motion that assumes that an object, considered as a …., moves along a …

A

point-like object; straight line

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14
Q

when the object travels at constant speed, the dots are

A

evenly spaced

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15
Q

when the object slows down, the dots get

A

closer

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16
Q

when the object moves faster and faster, the dots get

A

farther apart

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17
Q

we can represent motion in even more detail by adding … to each dot that indicate which … the object is moving and how … it is moving as it passes a particular position

A

velocity arrows; way; fast

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18
Q

dot diagrams + velocity arrows is

A

motion diagram

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19
Q

the longer the arrow, the … the motion

A

faster

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20
Q

vectors have … and …

A

direction; magnitude

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21
Q

velocity change arrow (Δv→) indicates change in … on …

A

velocity; motion diagram

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22
Q

a velocity change arrow is a … indication

A

qualitative

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23
Q

a velocity change arrow points in the same direction as the velocity arrows when object is …. it points in the opposite direction when the object is …

A

speeding up; slowing down

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24
Q

when velocity changes are the same for each time interval, all of the velocity change arrows will be the …, so we only need use … for the whole motion diagram

A

same length; one

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25
time described in two ways: time: the ... clock reading time interval (...): the ... clock readings
actual; Δt; difference in
26
time and time interval are
scalar quantities
27
position: object's ... with respect to the ...
location; coordinate system
28
displacement: ... quantity that defines the change in ... (...)
vector; position; Xf - Xi
29
distance: ... of ...
magnitude; displacement
30
path length: how ... the object moved as it traveled from ...
far; initial position to final position
31
the quantity determined through subtracting Xf-Xi is called .... or simply ...., appreviated...
x-scalar component of the displacement; x-component of the displacement; dx
32
kinematics: description of
motion
33
the slope of an x-t graph equals ... = ....
X2- X1 / t2 - t1 = Δx/Δt m/s
34
the slope of an x-t graph indicates how the object's ... changes with respect to ..., tells ... relative to ....
position; time; direction of motion; coordinate axis
35
the slope of an x-t graph is equal to
velocity
36
velocity = .. + ...
speed; direction
37
V= Δx/Δt is only for
constant velocity linear motion
38
speed is the ... and is always ...
magnitude of velocity; positive
39
V=Δx/Δt can be arranged to devise the following equation:
X2 = X1 + Vx(t2-t1)
40
applying X2 = X1 + Vx(t2-t1) for time zero, when initial position is X0, the equation can be written as
X= X0 + Vx*t
41
Rearranging the equation for an object's position (X= X0 + Vx*t ) yields ..., this is ... and is also the ... on the v-t graph
x - x0 = vx*t; | displacement; area
42
for motion with constant velocity, the magnitude of the displacement of an object is the ... between a v-t graph line and the .... between the time readings
area; time axis
43
displacement is the area with a + sign when velocity is ..., and area with - sign when velocity is ...
positive; negative
44
instantaneous velocity: velocity of an object at a
particular time
45
for accelerating objects, v = Δx/Δt can't be used to determine ..., but it can be used to find ...
instantaneous velocity; average velocity
46
acceleration characterizes the rate at which
velocity of an object is changing
47
when object is moving along a straight line and the slope of the v-t graph is constant, acceleration follows this formula:
ax = Δvx/ Δt
48
average acceleration during a time interval: a =
Δv/ Δt
49
If Δt is very small, acceleration defined by the equation Δv/Δt is .., not ...
instantaneous; average
50
units of acceleration:
m/s^2
51
it's possible for an object to have ... velocity and ... acceleration: e.g. when an object starts ..
zero; nonzero; moving from rest
52
when object starts moving from rest, Vi is
0
53
an object can have .. velocity and ... acceleration eg. if an object moves at ...
nonzero; zero; constant velocity
54
If, for linear motion, t0=0, acceleration can be defined as:
ax = (vx - v0x)/ t - 0
55
ax = (vx - v0x)/ t - 0 can be arranged to get
Vx = V0x + ax*t
56
(displacement from constant a) for constant acceleration, noting that displacement is the area for the v-t graph, we can find this area by separating the graph into a
triangle and rectangle
57
(displacement from constant a) area of the triangle is
1/2bh
58
(displacement from constant a) base in this case is ... which equals ..., as initial time starts at ... and is ...
Δt; t - 0; origin; 0
59
(displacement from constant a) height in this case
Δv
60
(displacement from constant a) area of triangle is therefore
A = 1/2(t - 0)(vx - v0x)
61
(displacement from constant a) vx - vox = ax*t so area of triangle can be rewritten as
A = 1/2(t)(axt) = 1/2ax*t^2
62
(displacement from constant a) area of rectangle is width * height which therefore =
Arect = Vx0 * (t-0)
63
(displacement from constant a) thus, the area between curve and time axis (displacement) is:
x - x0 = arect + atriangle | x = x0 + V0x*t + 1/2*ax*t^2
64
alternate equation for linear motion with constant acceleration
2ax (x - x0) = (Vx)^2 - (V0x)^2
65
we can represent the motion of a falling ball mathematically using the equations of motion for constant acceleration with Ay =
9.8 m/s^2
66
For free fall (vertical motion), Vy =
V0y + ay*t = V0y + (9.8 m/s^2)*t
67
for free fall, displacement equation with acceleration becomes, y =
y0 + v0y*t + 1/2(9.8 m/s^2)*t^2
68
the magnitude of an object's acceleration while falling without air resistance is given a special symbol, ..., where it = ...
g; 9.8 m/s^2
69
for an object that is at rest and remains at rest, the instant the object is not moving, its acceleration =
0 m/s^2