Charge
Is conserved always
Junction rule
I in = I out
Conservation of charge
Loop Rule
For any conductive loop, emf-v=0
Conservation of energy
Ideal Spring
obeys Hooke's law = "simple harmonic motion
Hooke's Law
F = -kx
Linear relationship between restoring force and displacement
Newton's First Law
-An object at rest will stay at rest
-a moving object will stay moving unless disturbed by an un balenced force.
Newton's Second Law
F=ma
Newton's Third Law
-For every action there is an equal and opposite reaction
-"Third law pairs
Center of Mass
-Where external force acts
-Where mass is concentrated
-If no external force, position is constant
X(com) = ( m1x1 + m2x2 ) / M(sys)
Velocity of Center of Mass
V(com) = ( m?v? + m?v? ) / M(sys)
Units for momentum
kg*m/s
Units for energy
Joules (J)
Units for voltage
Volts
Units for electric power
Watts
Moment of Inertia
point mass I=mr^2
cylinder I=1/2(mr^2)
Conservation of Mechanical Energy
When only conservative forces do work on an object, energy is conserved and described by the equation: ?E = ?KE + ?PE = 0
Longitudinal Wave
Moves parallel to propagation (sound)
Transverse Wave
Moves perpendicular to propagation
Vstring
where ? is mass/length
Constructive interference
where ?(1) = n*?(2) difference in length is an integer of whole wavelengths
Destructive interference
where ?(1) = n*?(2)/2 difference in lengths os a whole number of half wavelenghs
V of a wave
determined by medium, inversely proportional to square root of density
Beat frequency
occurs with two sound sources of different frequencies alternating between constructive and destructive interference.
f(beat) = | f1 - f2 |
Sound Intensity
Intensity = Power / Area
V of sound
Proportional to root of Temp in Kelvins
When T increases, V increases
Damped Oscillation
Energy is lost to other forms so ME(i) ? ME(f)
Rule of Small Angles
sin?(degrees) = ?(rad)
Rotational Period
T=2? ?(I/mgd) increases with Inertia
Rotation vs. Circular motion
Rotation - rotation around an axis
Circular motion - object moving in a circle due to centripetal force
No Slipping
V of any point of contact must be zero
0 = Vcom + Vt
Resistance
R = ? L/A. L is length of the conductor, A is cross-sectional area. ? is resistivity - determined by medium
Power relates to the physical property of
Brightness
Amplitude of a sound wave determines
Loudness
Frequency of a sound wave determined
Pitch
Unit for current
Amps (A)
I = ?q / ?t
rate of net charge flow in respect to time
Conductors
Allow charge to flow
Insulators
Don't allow charge flow
Unit of charge
coulomb (C)
Current flows from
High V to low V
Electric potential
?V=W/q, W is work needed to move test charge aka ?Ue
Conservation of Momentum
When there are no net external forces doing work on the system.
Conservation of Angular Momentum
no external torque doing work on the system
Rotational Kinetic Energy
KErotational = 1/2
I
?^2
W = ?KErot = ? ??
Angular Momentum
L = r?mv or I?
?L = ??t
Elastic Collision
KEi = KEf
Perfectly Inelastic Collision
Objects stick together
Resistors in Parallel
?v is = in all resistors
I is shared (junction rule) & depends of value of R
Sum of inverse of the resistances = inverse of R(eq)
Lowers total resistance, increases power, increases brightness!
Resistors in series
I is = in al resistors
?v is shared & depends on the value of R
Increases resistance, decreases power, decreases brightness!
Intensity will be zero when two speakers have
Same amplitude and ?d = n(wavelength)
Units for k of a spring
N/m
Without friction, a mass collides with a spring. What is conserved?
Momentum
NOT mechanical energy bc. force on impact is not conservative!
Rate at which energy is dissipated in a resistor is...
Power
Ohmic Resistor
A resistor that follows Ohm's Law
?v=IR
?p
0