Linear Kinematics:
x
= (vf + vi)/2
V
t
a
v
,
t
a
dv
= slope of a velocity vs time graph
dt
Dynamics
Σ F ma,
Ff FN
d2x
a 2
dt
v 2f v 02 2ax
Range equation: R = 2V o 2 (sin 2φ)/g = horizontal distance traveled if shot at angle
1
x v f t at 2
2
1
x v 0 v f t note: this is just average speed x time
2
x( or distance traveled) = ∫ v dt = area under a speed vs time graph
vectors: never mix x and y
dx
1
v
x v 0t at 2 ,
dt
2
Fg
G
vectors: never mix x and y
ixj=k
w mg
but against circle j x i = -k
( s is a maximum therefore can be less than calculated, and k is constant)
m1m2
r2
Fc mac ,
Fc m
v2
,
r
Fs kx
scalars. Direction is less important….easier……very little trig.
Dot product yields scalar projections: i∙i = 1, i∙j = 0
Energy:
W F d Fd cos , W Fdxcos = area under an F vs distance graph
W K , W U
U g mgh on a planet,
mm
Ug G 1 2 between objects (like Earth and Sun, apple and moon)
r
1 2
K mv
2
Total Mechanical Energy E = K + U
For satellites in circular orbit
Fc =Fg to find orbital velocity
U = K to find escape velocity
K = -U/2 and E = -GMm/2r where are is the separation between centers
U i Ki U f K f
if gravity is the only force in play
1
Us kx2
2
F = -dU/dx = negative of slope on a U vs x graph.
Know shapes of stable, unstable and neutral equilibrium.
W
= dU/dt
t
P Fv used mainly when sliding an object against friction at constant speed
P
Momentum vectors again; separate x and y
dp
= slope of a momentum vs time graph
p mv , pi p f , F
dt
J mv , J Ft , J Fdt = area under an F vs t graph
& Oscillation
Rotation
2π radians = 360°
,
t
1
0 t t 2
2
,
t
v r
s r
d
dt
at r
d
dt
1
i f t
2
Fc m 2 r
CM calculation: Pick a convenient origin then do
z
Xcm = Σmx/Σm. Next do y and
If there is no outside force acting, the motion of the CM will remain unchanged.
If an outside force is acting, F =ma find the acceleration of the CM.
If you are rotating about the CM
Other shapes
us I
r dm,
2
I mr 2
Ihoop = mr2
I disk = ½ mr2
I r 2dV
(called a volume integral if you did it in calculus)
If you are rotating about any axis a distance d from the center of mass
I p Icm
Md 2
1
K r I 2
2
L I ,
I ,
rF sin = rxF (RHR for direction)
L mvrsin
Kepler: for any satellite about a central star
4 2
T
2 ksa 3 , k s
, (k goes to 1 when AU’s and Years are used)
Gms
l
m
Tp 2
Ts 2
g
k
I
for the rocking oscillation of any shape of known I
mgd
2r
2
x Acost where A is the amplitude. (or use sine)
v
T
T
d2x
a A 2 cost , a 2 , a 2 x
v dx / dt A sin t ,
dt
Tcp 2