PHYS 112 Review.docx

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PHYS 112
Carey Bissonnette

PHYS 112 Review Chapter 13: Oscillations about Equilibrium Simple Harmonic Motion - Non constant acceleration - Periodic motion: motion that repeats itself - Oscillatory motion: periodic motion that moves back and forth over the same path Period (T): the time required for a motion to repeat, time required for one cycle of periodic motion Frequency: the number of oscillations per unit time: f=1/T Angular Frequency: w = 2πf = 2π/T Position: x(t)=Acoswt Velocity: v(t)=-Awsin(wt) 2 2 Acceleration: a(t)=-Aw cos(wt) = -w x(t) Where A is the amplitude of motion, w is the angular frequency of motion, and f is the frequency of motion A linear restoring force will give you simple harmonic motion. The linear restoring force tries to push the mass back to equilibrium position. Hooke’s Law: F= -kx = ma 2 KE= ½mv PE= ½kx 2 Energy doesn’t change when mass is doubled, however, maximum velocity does. Chapter 14: Waves and Sound Periodic disturbance – transfer of energy without transferring materials 2 kinds of waves: transverse and longitudinal Transverse: disturbance is perpendicular to direction of propagation Longitudinal: disturbance is parallel to direction of propagation v: velocity of wave (constant for constant medium) A: amplitude (height of disturbance) λ: wavelength, repeated disturbance f: frequency, number of full waves that pass a point T: period, time for one wavelength to pass a point v=distance/time=x/T=fλ Superposition principle: 2 waves travelling toward each other meet and pass through each other. Where the waves overlap you see the sum of the two waves: constructive interference (waves that give a larger amplitude), in phase, louder noise, r =r +nλ 1 2 destructive interference (waves that give a smaller amplitude), out of phase, quiet noise r1=r2+(n+1/2 )λ Sound: in solid medium: √ in fluid or gas medium: √ When a sound wave passes from air to water, wave speed must change (different medium). However, frequency does not change, as it is determined by the source. Now v= fλ, and because f is constant, and v changed, λ must also change. Sound source emits energy over time: Power of source – Sound intensity (power passing through an area): Intensity level (sound level): , where I0is the threshold of hearing, and β is in decibels. Standing waves on a String Standing Waves in an Air Column Chapter 19: Electric Charges, Forces, and Fields Static Electricity: like repels like, opposites attract Charge on one e = -1.602 x 10 -19C (C = Coulomb) -31 -27 m e 9.11 x 10 kg m =p1.67 x 10 kg 2 Coulomb’s Law: F = (k*q *q 1/r 2 To solve for the force acting on a charge, just add all the forces acting on the charge: 1. Draw a picture 2. Draw all the force vectors acting on the charge (direction) 3. Calculate magnitude and components of each foce 4. Add them up | | Point Charge: Chapter 20: Electric potential and Electric Potential Energy Work = W = F*d = F*dcosθ W=FΔx W=ΔKE=KE-KE f thii is a conservative force Uniform Electric Field: F=qE W=Fd=qEd Potential Energy ΔPE = -W = -(qE (xxxf) i (k*q *q)0r Electric Potential Difference: ΔV=V -V b ΔaE/q = -W/q ΔV=-Ed Capacitor: Electrical component used to store energy for a short period of time Battery: pumps charge and maintains a potential difference across battery Conductor: electrons free to move – metals binsulator: electrons are tightly bound to atoms – non-metal Current is the motion of electrons – traditional current involves the positive charges moving Capacitance: the measure of the ability of a capacitor to store charge: C=Q/V unit: farad, f Parallel Plate Capacitor: Dielectrics: a dielectric is an insulating material that increases the capacitance of a capacitor. The dielectric constant, k, reduces the electric field by a factor of k. the potential difference between capacitor plates is decreased by the factor k. Chapter 21: Electric current and direct current circuits Current: I=Q/t unit is Ampere, Amp; 1A=1C/s  I=V/R Electromotive force: emf, ε, is the potential difference between the terminals of a battery under ideal conditions Work done by a battery: W=ΔQ*ε Resistivity: ρ, the resistivity of a material determines how much resistance it gives to the flow of electron current. Ohm’s Law: V=I/R Resistance of a wire: R=ρ(L/A) Electric Power: P=IV P=(V )/R = I R 2 2 Power dissipation in a Resistor: P = I *R= V /R Series Parallel Capacitance Resistance Kirchhoff’s rules Junction Rule (Charge conservation): the algebraic sum of all currents meeting at a junction must equal zero. Currents entering the junction are taken to be positive, currents leaving are taken to be negative Loop Rule (Energy Conservation): the algebraic sum of all potential differences around a closed loop is zero. The potentia
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