One-Dimensional Kinematics (Ch. 2.1 - 2.7) Flashcards
1
Q
mechanics
A
- the study of objects in motion
- includes kinematics and kinetics
2
Q
kinematics
A
- describes how objects move and predicts the objects’ motion
- approaches problems with the kinematic equations
3
Q
kinematic variables
A
- distance (d)
- displacement (x)
- speed (s)
- velocity (v)
- acceleration (a)
- time (T)
4
Q
scalar quantity
A
- magnitude only
5
Q
vector quantity
A
- magnitude AND direction
6
Q
distance (d)
A
- the total length of travel
- always positive
- scalar quantity
- SI units: meter (m)
7
Q
displacement (x)
A
- the net change in position
- positive, negative, or zero
- vector quantity
- SI units: meter (m)
ΔX = Xf - Xi
8
Q
distance vs. displacement
A
- d is scalar and x is vector
- different magnitude if there is a change in direction
- x can be zero while d has magnitude if start and stop at the same point
9
Q
speed (s)
A
- the rate of change of the distance
- always positive
- scalar
- SI units: m/s
s = d/Δt
10
Q
velocity (v)
A
- the rate of displacement
- positive or negative
- vector quantity
- SI units: m/s
Vav = Δx/ Δt
11
Q
speed vs. velocity
A
- the magnitude of both will only be different if the distance and displacement are different
- if the object changes direction, the magnitude of the speed and velocity will be different
12
Q
average velocity vs instantaneous velocity
A
- average velocity: the rate of change of the displacement over a period of time
- instantaneous velocity: the change in the position at an instant of time
- the average v = the instantaneous v if the velocity is constant
13
Q
acceleration (a)
A
- the rate of change of velocity
- positive or negative (indicates the direction of a)
- vector
- SI units: m/s2
Vav = Δx/ Δt
14
Q
average acceleration vs instantaneous velocity
A
- if the acceleration is constant, the average acceleration is equal to the instantaneous acceleration
15
Q
the sign of acceleration
A
- indicates direction of acceleration
- the direction of acceleration is determined by the sign from the change in velocity, not by the direction an object is moving in
- acceleration does not have to point in the same direction as the velocity
- a negative acceleration does not necessarily mean the object is slowing down; it just means the acceleration is pointing in the negative direction
16
Q
velocity vs. acceleration
A
- when the velocity and acceleration of an object have the same sign (point in the same direction), the speed of the object increases.
- when the velocity and acceleration of an object have opposite signs (point in opposite directions), the speed of the object decreases
17
Q
the relationship of speed to velocity and acceleration
A
- increases when velocity and acceleration have the same sign (direction)
- decrease when velocity and acceleration have the opposite sign (direction)
18
Q
graphing relationships of velocity
A
- the slope of a position vs time graph = velocity
m = Δx / Δt = V
19
Q
graphing relationships of acceleration
A
- the slope of the velocity vs. time graph = acceleration
m = Δv / Δt = a
20
Q
graphs of constant position
A
- the slope of a position vs time graph is 0, as it is constant
- therefore, v = 0 and a = 0
21
Q
graphs of constant velocity
A
- the position vs time graph displays a slope, indicating a change in position
- the slope of the velocity vs time graph is zero, indicating a constant velocity
- therefore, a = 0
22
Q
graphs of constant acceleration
A
- both the position vs time graph and the velocity vs time graph indicate changes in position and velocity
- therefore the slope of a is zero, and it has a constant acceleration
23
Q
position vs time graph
A
- a graphical representation of velocity
- the average velocity is the slope of the straight line connecting two points corresponding to a given time interval
- the instantaneous velocity is the slope of the tangent line (the straight line that just touches the curve) at a given instant of time
- with constant velocity, the average velocity over any time interval is equal to the instantaneous velocity at any time
24
Q
velocity vs. time graph
A
- a graphical representation of acceleration
- the average acceleration is the slope of the straight line connecting two points corresponding to a given time interval
- the instantaneous velocity is the slope of the tangent line (the straight line that just touches the curve) at a given instant of time
- with constant acceleration, the average velocity over any time interval is equal to the instantaneous velocity at any time
25
Q
Kinematic equations
A
26
Q
free fall
A
- an object only under the influence of gravity (air resistance is negligible)
27
Q
acceleration in free fall
A
- ALL objects experience a downwards acceleration of 9.8 m/s2 regardless of mass
- At EVERY point of the object’s travel, the acceleration is 9.8 m/s2 downwards
- “at every second, add 9.8 m/s velocity in the negative direction”
28
Q
velocity and acceleration at the top of an object’s free fall
A
- the velocity = 0
- the acceleration = 9.8 m/s2 downwards
29
Q
the velocity of the object as it travels up
the velocity of the object as it travels down
A
- the object slows down as it moves up, as a and v are in opposite directions
- the object speeds up as it moves down, as a and v are in the same direction
30
Q
the magnitude of velocity at the same heights
A
- at the same height, the velocity up and the velocity down have the same magnitude but opposite directions
