Download Honors Physics – 1st Semester Exam Review

Honors Physics – Final Exam Review
I. Math Review for Physicists
Vocabulary: accuracy, precision, linear, exponential, inverse, root curve, dimensions, independent variable, dependent variable
sin   opp/ hyp , cos  adj / hyp , tan  opp/ adj , Pythagorean theorem: a2 + b2 = c2
1.
Triangles:
2.
Significant Figures
a. Sig figs with addition/subtraction (fewest decimal places)
b. Sig figs with multiplication/division (fewest sig figs in any of the factors)
Units/Unit Conversion
a. Standard SI units (kg, m, s, C, etc.)
b. Conversions (giga, mega, kilo, hecta, deka, deci, centi, milli, micro, nano, pico)
c. Dimensional consistency (check to see if the units in an equation “work”)
Linear Relationships
a. Slopes/intercepts
b. Meaning of the slope
c. Writing equation from a linear graph
d. Using the equation to answer questions about the data
Graph Shapes (recognize shapes)
a. Linear: y = kx + b
b. Exponential: y = kxn + b
c. Inverse: y = kx-n + b
d. Root
Experimental Conditions
a. Independent and dependent variables
b. Recognize which variables are held constant
3.
4.
5.
6.
II. Mechanics Section 1: Position, Velocity and Acceleration
Vocabulary: vector, scalar, position, distance, displacement, speed, velocity, strobe diagram, motion map, frame of reference, average velocity,
instantaneous velocity, average acceleration, instantaneous acceleration
1.
3.
Strobe diagrams and motion maps
a. How to draw and interpret them
b. Frame of reference
x vs. t, v vs. t, a vs. t graphs
a. finding equation that describes a linear graph
b. converting among graphs
c. converting between graphs and verbal descriptions
d. converting between graphs and strobe diagrams/motion maps
e. slope of x vs. t curve = instantaneous velocity
f. slope of v vs. t curve = instantaneous acceleration
g. area under v vs. t curve = x
h. area under a vs. t curve = v
Comparing motion of two objects graphically
4.
v
5.
Vectors (displacement, velocity, acceleration, force, momentum) and scalars (distance, speed)
2.
x
v
, a
t
t
III. Mechanics Section 2 – One Dimensional Kinematics (constant acceleration)
Vocabulary: freefall, kinematics
1.
2.
Stacks of kinematics curves
Equations
a.
b.
c.
3.
x  1 vi  v f t
2
2
x  vi t  1 at 
2
v f  vi  2ax
2
2
g = 9.8 m/s2 downward (any object in the air on earth has an acceleration of g!)
4. Describe x, v, and a for an object tossed straight up into the air
Goal 2: Two Dimensional Kinematics (motion in two dimensions!)
IV. Mechanics Section 4 – Projectile Motion
Vocabulary: projectile, trajectory, horizontal component, vertical component, range, hang time/flight time, frame of
reference, air resistance, apogee, perigee
1. Projectile: any object on which gravity is the only force
2. Acceleration of a projectile (on Earth) is always g (9.8 m/s2)
3. Divide problem into horizontal and vertical parts
a. Horizontal
i.
Horizontal component of velocity is always constant (a = 0)
ii.
v
x
t
b. Vertical
i.
Vertical acceleration is always = g
ii.
2
All equations from last unit apply, and acceleration = g: y  vi t  1 g t  and
2
v f  vi  2 gy
2
2
c. Any given quantity that is neither horizontal nor vertical must be resolved into its components
4. For a projectile launched horizontally, flight time depends only on the height from which it was launched
5. For projectiles launched at angles: REMEMBER TO RESOLVE THE INITIAL VELOCITY INTO
COMPONENTS!!
6. Effect of air resistance on trajectory
7. Satellite Motion
V. Mechanics Section 5 – Circular Motion
Vocabulary: uniform circular motion, circumference, tangential/linear velocity, centripetal acceleration, centripetal force,
centrifugal force
1. Centripetal vs. centrifugal force and Newton’s 1st Law
2r
, where T is the period
T
2.
v
3.
aC 
v2
mv 2
, FC 
r
r
4. Centripetal force is a net force!
5. Identify centripetal forces on different objects (gravity, tension, friction (unbanked curve), friction &
normal force (banked curve), etc)
6. Remember F f  FN
7. Newton’s Law of Universal Gravitation: Fg 
Gm1m2
r2
Goal 3 and 4: Forces
VI. Mechanics Section 3 – Forces
Vocabulary: Force, inertia, agent, object, net force, terminal velocity, equilibrium, contact force, field force, force of
gravity, normal force, force of static friction, force of kinetic friction
1. Newton’s Laws of Motion
a. Inertia
b. Fnet = ma
c. Equal and opposite force pairs (agent/object notation)
2. Types of forces
a. Applied, tension, kinetic friction, static friction, air resistance, normal, buoyant
b. Gravitational, electric, magnetic
3. Free-body diagrams
a. Draw them
b. Calculate individual forces
c. Calculate net force
d. Objects on flat ground or on an incline
4. Equilibrium Forces
a. Find unknown force when Fnet = 0
b. Find force that will make Fnet = 0
5. Force of friction
a. Kinetic and static friction
b. Ff = FN
6. Torque
a. Torque = perpendicular force x lever arm
b. Formula:  = F┴∙d
Goal 6: Momentum and Impulse
VII. Mechanics Section 6 – Momentum and Impulse
Vocabulary: inertia, momentum, elastic, inelastic, impulse
1. Remember: Inertia
2. Momentum
a. Takes into account both inertia (mass) and velocity
b. p = mv
c. Momentum is a vector
d. Units: kg∙m/s
3. Conservation of Momentum
a. Total momentum is always conserved (The most unbreakable law in the universe!)
b. For the system as a whole: pinitial = pfinal
4. To solve momentum problems:
a. Define an initial state and a final state
b. Write an equation for the initial momentum
c. Write an equation for the final momentum
d. Set them equal and solve pinitial = pfinal
5. Elastic (“bouncing”) and Inelastic (“sticking”) Collisions
6. Impulse
a. Impulse is a change in momentum.
b. Ft = mv = p
c. For impulse calculations where the force is changing, use the average force
d. Practical applications (bat and ball, car airbags, gymnastics mats, safety nets, car crashes, jackhammer)
Goal 5 and 8 – Work, Energy, and Thermodynamics
Vocabulary: Energy, work, power, kinetic, gravitational potential, elastic potential, spring constant, internal energy, conservative force,
heat, thermal equilibrium, specific heat, entropy
1. Energy
a. the ability of an object to produce change in itself or its environment
b. unit – Joule (J) = Nm
2. Ways to represent energy
a. Energy pie charts
b. Energy flow diagrams
c. Energy bar graphs
3. Forms of Energy Storage
a. Kinetic Energy – Is the object moving?
i. KE = ½ mv2
ii. KE is a scalar (technically depends on speed, not velocity)
iii. Soup can lab: translational and rotational KE
iv. KE is conserved in elastic collisions, but not in inelastic collisions
b. Gravitational Potential Energy – Is the object some distance above the ground (or other reference point)?
i. GPE = mgh
ii. Must pick a reference point
c. Elastic Potential Energy – Is there a spring or other elastic object that is either stretched or compressed?
i. EPE = ½ kx2
ii. x is the displacement from rest (non-stretched or compressed) position
iii. EPE = EPEf - EPEi
iv. F = kx (Hooke’s Law – force needed to stretch/compress a spring)
d. Chemical Energy – Energy stored in chemical bonds
e. Internal (Thermal) Energy – Is there friction or some type of collision/compression?
4. Methods of Energy Transfer
a. Working – It’s working if there is a change in energy and it’s not either of the other two!
b. Heating – Change in temperature
c. Radiating – emitting electromagnetic waves
5. Work is a change in energy (W = E)
a. W = E = Fx
b. W is + if energy is put into the system
c. W is – if energy is removed from the system
6. Power
a. The rate at which energy is transferred
b. Unit – Watt (W) = J/s
c.
7.
P
W E

t t
Conservative and Non-conservative forces
a. Conservative – energy transfer is reversible; E depends only on the initial and final positions.
b. Non-conservative – energy transfer is not reversible; E depends on the total distance traveled (ex. Friction)
8. Heating
a. Temperature – the average kinetic energy of the molecules in a substance
b. Conduction (materials in contact) and convection (motion of a fluid)
c. Specific heat
d. Q = mcT
9. Achieving Thermal Equilibium (two substances of different temperatures in contact)
a. Qlost = Qgained
b. –m1c1T1 = m2c2T2
c. Calorimeter
10. Change in internal energy = working + heating
a. U = Q + W
b. Remember to use the correct signs!
11. 1st Law of Thermodynamics – Conservation of energy
12. 2nd Law of Thermodynamics
a. Thermal Energy flows spontaneously from a hot object to a cooler one
b. One cannot convert thermal energy completely into useful work (eff = 1 – work/fuel)
c. Every isolated system becomes more disordered as time passes (Entropy)
Goals 9 and 10: Electricity and Magnetism
Vocabulary: insulator, conductor, semiconductor, conduction, induction, electric potential difference, series, parallel,
paramagnetic, diamagnetic, ferromagnetic, motor, generator
1.
2.
3.
Electrostatics
a. Electric Charge and Charge Transfer
i. Properties of charge (likes/unlikes, conserved, quantized)
ii. Insulators/Conductors/Semiconductors
iii. Milliken Oil Drop Experiment (showed charge is quantized)
iv. Charging by conduction/induction
v. Induced charge separation (conductor)/polarization (insulator)
b. Coulomb’s Law
i. F = kq1q2/r2
ii. Electric force is a field force, generally stronger than gravity
iii. Apply to two charges or multiple charges
c. Electric Field Lines
i. away from +, toward –
ii. closer lines  stronger field
iii. direction of field at a point is the tangent to the field line at that point
d. Electric Potential Difference
i. Volt = J/C
ii. V = W/q
iii. V = Ed
Electric Current
a. I = Q/t (Ampere = C/s)
b. Conditions for Current Flow
i. Electric potential difference
ii. Closed path
c. DC Circuits
i. Schematic Circuit Symbols
ii. Ohm’s Law: V = IR
iii. Series Circuits: I is same everywhere
VT = V 1 + V 2 + V 3 + …
RT = R1 + R2 + R3 + …
iv. Parallel Circuits: IT = I1 + I2 + I3 + …
V is same everywhere
1/RT = 1/R1 + 1/R2 + 1/R3 + …
v. Complex Circuits – simplify
d. Power
i. P = IV = I2R (unit: Watt)
ii. Energy dissipated by a circuit element: E = Pt
iii. Units of energy (J, kWh)
Magnetism
a. Different from electric force – can attract and repel; magnetic poles cannot be isolated
b. Magnetism basics
i. Magnetic field produced by a moving electric charge
ii. Magnetic domains
iii. “hard” and “soft” magnetic materials
iv. paramagnetic, diamagnetic, ferromagnetic
c. Magnetic Fields
i. Away from North, towards South
ii. Always complete circles (because poles can’t be isolated)
iii. Created by current carrying wires (right-hand rule, curved fingers)
d. Force on a charged particle in a magnetic field
i. Right-hand rule, open fingers
ii. F = qvB
iii. Charged particle in a magnetic field travels in circular path
e. Force on a current-carrying wire in a magnetic field (right-hand rule, open fingers)
f. DC Motors and Generators
i. Motors: How they work
ii. Generators: V = Blv (induced potential difference = mag field strength x length of conductor in field x velocity
of conductor)
Goal 7 – Waves and Optics
1. Simple Harmonic Oscillator/Simple Harmonic Motion
a. Pendulum: T depends on l and g (T2 proportional to l/g)
b. Spring: T depends on m and k (T2 proportional to m/k)
c. Period, amplitude, frequency
d. f = 1/T
2. Wave
a. Oscillating disturbance traveling through space (sine curve)
b. Waves transfer energy
c. Crest, trough, amplitude, wavelength, frequency
d. Transverse waves (electromagnetic, aka. “light”), longitudinal waves (sound)
e. Medium (light does not require a medium, sound does)
f. Intro to Waves Lab
g. v = f
3. Sound
a. Speed of sound in various media (slowest in gases, fastest in solids; faster in higher temperature gases;
faster in low molecular weight gases)
b. Sound Activity (higher f  higher pitch; amplitude  loudness; beat frequency = difference between two
frequencies; waveform shapes
4. Superposition
a. Constructive and Destructive Interference
b. Interference pattern (beats, ripple tank)
c. Standing Waves (nodes, antinodes)
d. Standing wave (on string or open tube): L = n/2
5. Doppler Effect
a. apparent change in frequency and wavelength (not speed!)
b. due to relative motion between source and observer
c. for light: “red shift” and “blue shift”
d. Bow waves and Sonic booms
6. Interaction of Waves and Media
a. Transmission (transparent, translucent, opaque, reflecting)
b. Reflection
- Reflection from free and fixed ends
- Normal to the surface
- i = r
- Specular and Diffuse Reflection
c. Refraction (waves enter a new medium and change speed)
- n = c/v = o/n
- n1/n2 = v2/v1
- wave slows down (n2>n1), bends toward normal
- wave speeds up (n2<n1), bends away from normal
- Snell’s Law: n1sin1 = n2sin2
- dispersion (prism, rainbow)
d. Total Internal Reflection
- Only when going from higher to lower n
- Critical angle: c = n1/n2 where n1>n2
e. Diffraction
7. Light
a. Electromagnetic Spectrum
b. Speed of Light
8. Optics
a. Ray diagrams
b. Real/virtual, enlarged/reduced/neither, upright/inverted
c. M = di/do = Si/So
d. 1/f = 1/di + 1/do