SOHCAHTOA
[
]
[
]
[
]
[
]
[
]
2
2
/
v
x
L T
L
a
t
T
T
t
=
=
=
=
2
2
2
r
x
y
=
+
2
4
2
b
b
ac
a

±

f
i
X
X
X
∆
=

.
.
.
tot dist
Avg Speed
tot time
=
X
V
t
∆
=
∆
u
v
V
a
t
∆
=
∆
v
2
1
2
h
at
=
D
V T
=
⋅
0
x
a
=
9.81
y
a
= 
o
V
V
at
=
+
2
1
2
o
X
V t
at
∆
=
+
2
2
2
f
o
V
V
a X
=
+
∆
2
2
x
y
V
V
V
=
+
1
tan
y
x
V
V
θ

=
cos
x
o
o
V
V
θ
=
sin
y
o
o
V
V
θ
=
F
ma
=
∑
u
v
w
mg
=
Atwood’s Machine:
2
1
1
1
2
m
m
a
g
m
m

=
+
2
1
1
2
m
m
T
g
m
m
⋅
=
+
s
f
F
= 
,
,
,
s
s
F
f
F
f
↑
↑
↓
↓
k
F
f
=
max
s
s
f
f
n
μ
=
=
⋅
k
k
f
n
μ
=
⋅
s
k
μ
μ
1
2
(
)
0
T
T
mg
+

=
To Find Largest Angle:
(
29
1
tan
s
θ
μ

=
sin
cos
k
incline
a
g
g
θ
μ
θ
↓
=

(
29
new
o
S
g
S
a
g
=
+
2
1
1
2
k
m g
m g
a
m
m
μ

=
+
Relative Velocity
: the velocity of an object relative to the velocity of the observer
AB
AE
BE
V
V
V
=

AB
AE
BE
r
r
r
=

●
AE
r
=
position of car A as measured by E
●
BE
r
= position of car B as measured by E
●
AB
r
= position of car A as measured by car B
Avg. Velocity:
slope of a straight line connecting the final/initial points.
Sig. Digits:
+/ (smallest # of decimal places of any term) x/ (digits in final answer = # w/
the least digits).
Dynamics:
study of motion and physical concepts (force & mass).
Kinematics
: part of dynamics that describes motion w/o cause.
Vector:
magnitude and direction.
Scalar:
only magnitude.
Newton’s 1
st
Law:
an object moves with a velocity that is constant in magnitude & direction, unless acted on by
a NONZERO net force. “objects move b/c the opposite force is exherted on a diff. object then the one being moved”.
Inertia
: tendency of an object to continue
in its original state of motion; it’s a property of matter to resist changes in motion.
Mass
: measure of an objects resistance to changes in its motion due to a force
(kg)
*greater the mass, the less it accelerates under a force, greater its inertia.
Newton’s 2
nd
Law:
accel. of an object is directly proportional to the net force acting
on it, inversely prop to its mass.
Gravitational Force
: mutual force of attraction btwn any 2 objects in the universe (weakest of all fundamental forces).
Newton’s Law of Gravitation
: every particle attracts every other particle w/ a force that is directly proportional to the product of the masses, inversely prop. to the
square of the distance between them.
Newton’s 3
rd
Law:
Forces in nature come in pairs. Force exerted by object 1 on 2 is equal to the opposite force exerted by
object 2 on 1. (action – reaction).
Tension:
magnitude of the force exerted along a rope – it’s the same at all points on the rope.
tot
E
KE
PE
=
+
av
F
a
m
=
Work
F
x
=
∆
cos
W
F
x
θ
=
∆
av
F
a
m
=
2
1
2
KE
mv
=
2
2
1
1
2
2
net
f
i
W
mv
mv
=

PE
mgy
=
(
)
w
F
x
Power P
Fv
t
t
∆
=
=
=
∆
∆
Work:
Scalar Quantity, only the component parallel to displacement does work.
KE:
Scalar Quantity (KE on earth = KE on moon).
Conservative Force:
(gravity) Does not depend on a path.
NonConservative:
(friction/heat/sound) Depends on a path.
Conservation of Energy:
energy can’t be created or
destroyed ONLY transferred from one form to another.
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 Spring '09
 LUI
 Force, Heat, Angular Acceleration, Velocity, initial velocity

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