Midyear Review Regents Physics
(Not on the Reference Tables)
Fundamental units
Mechanics
Mass (m): = inertia, amount of matter, constant from place
to place, units: kg
Quantity
Units
Symbol
Length
meter
m
Mass
kilogram
kg
Time
second
s
Weight (Fg): = force of gravity, changes from place to
place, units: N
Formula:
Fg = mg
Equilibrium: no net force, no acceleration, constant
velocity or at rest, forces form a closed figure.
Concurrent vectors:
are added tip to tail.
Component vectors:
any vector has both X and Y
components. Add components to get resultant.
V2 = Vx2 + Vy2
Angle : = tan-1[Y/x]
Resultant force = Fnet
: head-to-head and tail-to-tail
with components
Derived units
Quantity
symbol
Velocity
m/s
acceleration
m/s2
N/kg
force
Momentum
N
Kg m/s
kg m/s
Ns
Work, Heat
Energy
J
Nm
Voltage
V
J/C
Frequency
Hz
1/sec
Period
sec
&
Impulse
also
Kg m2/s2
Newton’s Law of Universal Gravitation
Equilibrant:
Gm1m2
Fg 
r2
equal and opposite to resultant
Two names for little “g”:
1) acceleration due to gravity, units: m/s2, formula: g = GM/r2
2) gravitational field strength, units: N/kg, formula: g = Fg/m
Vectors
Scalars (magnitude
only)
Distance
Speed
Mass
speed
Anything else!
Vectors (magnitude and direction) –
only 9!
Displacement
Velocity
Acceleration
Force (weight, normal force, etc.)
Momentum
Impulse
Fields (gravitational, electric,
magnetic)
Resultant
Concurrent
Equilibrant
Maximum 2
Θ = 00
Minimum 2
Θ = 1800
5
5
7
3
Triangle rule  sum of any 2 sides ≥ third side
for forces to be in equilibrium
Inclined Plane
Newton’s Third Law: Whenever A exerts force on B, B exerts
equal/opposite force on A. (Action/reaction pairs: bat and ball, Earth
and Moon, hammer and nail)
FA FF FT
FN
F║ = m g sinθ
Forces are the same but the effects of the forces are not:
FG
mA = Ma
F┴ = m g cosθ
Circular Motion
Friction
Static friction (at rest) = applied force until motion starts
Kinetic friction (in motion) is constant
Maximum static friction is greater than kinetic friction
d
Constant Velocity
Graphs of Motion
v
t
Slope = velocity
t
Slope = acceleration
Area = displacement
Two Types of Motion
Constant Acceleration
Forces are balanced
Fnet = 0, a = 0
In equilibrium
Newton’s first law
Forces are unbalanced
Fnet ≠ 0, a ≠ 0
not in equilibrium
Newton’s second law
Distance v.
time
Distance v. Speed v.
time
time
Speed v.
time
Acceleration v.
time
Acceleration v.
time
Projectiles
Horizontal Launch
x
Y
d
h
t
The same
a
0
9.81
vi
vi
0
vf
vi
vavg
vi
Angle Launch
x
dx = Vxt
Y
Whole
half
0
Vx
9.81
Vy
vf
Vx
0 (top)
vavg
Vx
Horizontal – constant speed
Vertical – constant acceleration
d
t
a
vi
T1/2 = Viy/9.8
Max range 45o max time 90o
V2 = Vx2 + Vy2
Angle : = tan-1[Y/x]