Accelerated / Honors Physics Review Packet (for studying for ...
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Transcript of Accelerated / Honors Physics Review Packet (for studying for ...
Motion Graphs:
• Displacement:
€
Δx = x2 − x1
• Average Speed:
€
s =dt
• Average Velocity:
€
v =Δxt
• Average Acceleration:
€
a =Δvt
• x-‐t graphs: slopes give velocities • v-‐t graphs: slopes give accelerations while areas give displacements • a-‐t graphs: area gives change in velocity
Equations of Motion (only to be used of acceleration is constant):
•
€
v2 = v1 + at •
€
v22 = v1
2 + 2aΔx •
€
Δx = 12 at
2 + v1t •
€
Δx = 12 t(v1 + v2)
•
€
x2 = 12 at
2 + v1t + x1 (to be used in “chase” problems) Vectors:
•
€
vpg = vpw + vwg (P: Plane, G: ground, W: wind)
Projectile Motion:
• Throw ups / Come downs: 1) Draw a picture, choose 2 critical points to work between 2)
€
vtop = 0 3)
€
Δtup = Δtdown and
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vthrow = −vcatch (if thrown and caught at same height) • Horizontal Projectiles (ex: ball rolls off table):
1) Draw a picture, choose 2 critical points to work between, Set up two columns (x & y) 2)
€
v1y = 0,
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ay = −9.8 3)
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Δx = vxt (since
€
ax = 0) 4) Only “t” can cross between X & Y columns
• Angled Projectiles: 1) Draw a picture, choose 2 critical points to work between, Set up two columns (x & y) 2) Break up initial velocity vector (
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v1x = v1 cosθ and
€
v1y = v1 sinθ ) 3)
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vtop,y = 0,
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ay = −9.8
4)
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Δttop = Δtland and
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R =v12 sin(2θ )g and
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h =v12 sin2(θ )2g (on level ground)
Accelerated / Honors Physics Review Packet (for studying for the Midterm and Final Exams)
Newton’s Laws:
• 1st Law: An object in motion (or at rest) will remain in motion (or at rest) unless acted upon by an unbalanced, external force.
• 2nd Law: F = ma • 3rd Law: For every action force there is an equal but opposite reaction force. • W = mg •
€
Ff = µFN • g = 9.8 m/s2 • Lawnmowers (pushed downward):
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F cosθ − Ff = ma and
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FN = mg+ F sinθ • Wagons (pulled upward):
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F cosθ − Ff = ma and
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FN = mg − F sinθ • Inclines (sliding downward):
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W|| − Ff = ma and
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FN = mgcosθ and
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W|| = mgsinθ • Atwood machine (2 masses hanging over a pulley):
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Mg −T = Ma and
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T −mg = ma and
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Mg −mg = (M +m)a
• Box on table pulled across by a pulley with a mass hanging off the side of the table:
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T − µMg = Ma and
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mg −T = ma and
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mg − µMg = (M +m)a
• “Constant Velocity” implies that: 1) a = 0 2) FNET = 0 Work & Energy:
•
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W = F||Δx (+ work is when F & Δx are in the same direction) • Wagons (pulled at an angle):
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Wpuller = (F cosθ )Δx and
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Wfriction = −FfΔx and
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Wtotal = F cosθ − Ff( )Δx
• F-‐x graphs: area under the graph is work (+ area is + work, -‐ area is – work) • Positive Work means energy was ADDED to the system (-‐ work à energy is removed) •
€
KE = 12mv
2 •
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PEg = mgh • Hookian Springs: F = kx (where k is the spring stiffness) and
€
PEspring = 12 kx
2 • Conservation of Energy:
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W = E2 − E1 = (KE + PEg + PEspring )2 − (KE + PEg + PEspring )1
• Power:
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P =Wt and
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P = Fv
• Block sliding down hill:
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−(µmgcosθ)d = 12mv2
2 − ( 12mv12 +mgd sinθ)
• Roller Coaster:
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12mv1
2 +mgh1 = 12mv2
2 +mgh2 • Loading the Pendulum:
€
W = mg(l − lsinθ) where
€
h = mg(l − lsinθ) comes from the “pendulum pennant”
Impulse & Momentum:
•
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p = mv
•
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FΔt = mΔv = mv2 −mv1 = Δp = p2 − p1 • F-‐t graphs: area under the curve equals impulse OR change in momentum • Conservation of Momentum:
“bounce”
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m1v1 +m2v2( )i = m1v1 +m2v2( ) f “stick”
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m1v1 +m2v2( )i = m1 +m2( )v f
“explosion”
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m1 +m2( )vi = m1v1 +m2v2( ) f
• Elastic Collision: energy is conserved • Inelastic Collision: energy is lost (objects move separately afterward) • Perfectly Inelastic Collision: STICK, and energy is lost • Minimum Separation (objects move at same speed momentarily at this moment):
€
m1v1 +m2v2( )i = m1 +m2( )v f and
€
12m1v1i
2 + 12m2v2i
2 = 12 (m1 +m2)v f
2 + 12 kx
2 + Epermant _ deform Circular Motion:
•
€
ac =v 2
R (inward)
•
€
Fc =mv 2
R
•
€
T =2πRv and
€
f =1T
•
€
INS −OUTS = Fc =mv 2
R
• car going around a flat turn:
€
Ff = Fc → µmg =mv 2
R→ v = µgR
• car going around a banked turn: frictionless:
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v = (tanθ )gR and
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FN =mgcosθ
max speed (before slipping upward):
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v =gR(tanθ + µ)(1− µ tanθ)
min speed (before slipping downward):
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v =gR(tanθ − µ)(1+ µ tanθ)
• swing ride (conical pendulum):
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T sinθ =mv 2
R and
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T cosθ = mg
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v = (tanθ )gR and
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T =mgcosθ
and
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R = lsinθ
• Vertical Circles (ball on string):
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T −mg =mv 2
R→ T =
mv 2
R+mg (bottom, max Tension)
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mg+T =mv 2
R→ T =
mv 2
R−mg (top, min Tension)
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T =mv 2
R (side)
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v = gR (min velocity needed at top to complete circle)
• Loop-‐de-‐Loops: For cars/bikes, replace T in above equations with FN.
For planes, replace T in above equation with either FN or FL. • Woop-‐de-‐Doos:
Bottom of Dip:
€
FN −mg =mv 2
R→ FN = mg+
mv 2
R
Top of Hump:
€
mg − FN =mv 2
R→ FN = mg − mv
2
R
€
# of g's =FNW
=FNmg
€
v = gR (critical velocity before leaving ground
Planetary Mechanics:
•
€
ac =v 2
R ,
€
Fc =mv 2
R ,
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T =2πRv ,
€
f =1T
•
€
Fg =GMmR2
(
€
Fg ∝ m ,
€
Fg ∝ M ,
€
Fg ∝ mM ,
€
Fg ∝1R2)
•
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g =GMR2
(
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g∝ M ,
€
g∝ 1R2)
•
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G = 6.67 ×10−11 N ⋅ m2
kg2
• Kepler’s Laws:
1st: Planets orbit in elliptical paths with sun at Focus 2nd: planets sweep out equal areas in equal amounts of time (sling shot effect)
3rd:
€
K =R3
T 2
• altitude = h = R – rplanet
• satellite equation(s):
€
v =GMR
and
€
ac = g
Static Electricity:
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me = 9.11E − 31kg mp =1.67E − 27kgq = ±ne (e =1.602E -19C)
Fe =kqQd2 (k = 8.99E9 N ⋅ m
2
C2 )
E =Feq
(for a uniform electric field)
E =kQd2 (for the non - uniform electric field around a point charge)
PEE = qEd (energy stored in a UNIFORM electric field)
PEE =kqQd
(energy stored in a non - uniform electric field around point charges)
ΔV =ΔPEE
q(Voltage Difference OR Electric Potential Difference)
ΔV = Ed (Electric Potential Difference, or Voltage difference, in a UNIFORM electric field)
Electric Circuits:
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Q = ne
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e =1.602 ×10−19C
€
I =Qt
€
R =VI
or V = IR
€
R = ρLA⎛
⎝ ⎜
⎞
⎠ ⎟ (where ρ is resistivity)
€
R = Ro 1+αΔT( ) (temp dependence of R)
€
P =Et
or P = IV or P = I2R or P =V 2
R
SERIES CIRCUITS: current is the same through all resistors
€
Req = R1 + R2 + ..... and
€
I = I1 = I2 = .... and
€
V =V1 +V2 + .... PARALLEL CIRCUITS: voltage is the same across each resistor
€
1Req
=1R1
+1R2
+ ..... and
€
I = I1 + I2 + .... and
€
V =V1 =V2 = ....
Kirchoff’s Rules:
1) The sum of the voltages around a closed loop is zero. 2) The current into a node equals the current out of a node.
Magnetism:
•
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F = qvB⊥ (charged particle moving through a B-‐field) •
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F = B⊥Il (force felt by a current-‐carrying wire) •
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ΔV = Blv (voltage induced in a loop of wire where one end of the loop is moved through a B-‐field)
• Right-‐Hand-‐Rules:
o RHR1 – Thumb (v), Fingers (B), Palm (Force felt by + charge) o RHR2 – Thumb (I), Fingers curl in direction of B-‐field (around straight wire) o RHR3 – Fingers (curl around coil in current direction), Thumb (point in direction of the
field lines passing thorough the loop)
• Transformers
o
€
Ns
Np
=Vs
Vp
=IpIs
o Ideal T-‐former:
€
Pp = Ps or
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IpVp = IsVs
o Non-‐Ideal T-‐former:
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e =IsVs
IpVp
× 100%
Mirrors/Lenses:
•
€
v = fλ
•
€
1f
=1do
+1di and
€
hiho
= −dido
= M
•
€
n =cv and
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n1 sinθ1 = n2 sinθ2 and
€
θcritical = sin−1 n2n1
⎛
⎝ ⎜
⎞
⎠ ⎟
Waves:
•
€
v = fλ • Young’s Double Slit Experiment:
o
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λ =xdnL or
€
λ =d sinθn
because
€
xL
= sinθ
λ = wavelength of light used (m) x = distance from central fringe (m) d = distance between the slits (m) n = the order of the fringe L= length from the screen with slits to the viewing screen (m) θ = angle between central fringe and the fridge being measured
o n = 0 (Central Fringe), n = 1 (1st order fringe), etc, etc, etc