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Impulse Momentum theory
A force acting on a mass during a time causes the mass to change its momentum.
unit: Newtons per second
If total momentum of a system is constant, momentum is ____________.
3 types of conservation of momentum
- 1. Recoil
- 2. Inelastic Collision
- 3. Elastic Collision
The momentum of the bullet must be equal & opposite to the mmentum of the rifle.
An inelastic collision occurs when 2 colliding objects stick together after impact. Momentum is conserved but kinetic impact is not.
In an elastic collision, the colliding objects bounce off each other, and momentum is conserved, as well as kinetic energy.
- W=scalar, not a force vector
- units: joules (J)
Energy & 3 types
- Energy is the ability to do work.
- unit: joules (J)
- 1. Potential Energy
- 2. Kinetic Energy
- 3. Heat Energy
The amount of work done on a system is exactly equal to the change in energy of the system.
- The energy a system has because of its position or configuration.
- F = mg
- s = h
- PE = mgh
- PE = Potential Energy
- KE = kinetic energy
- the energy an object has because it is moving.
Law of Conservation of Energy
Energy is conserve (constant during any process) in isolated, or insulated systems-systems in which the particles do not interact with objects outside the defined system.
- The rate at wich work is done.
- P = work/time
- units: joules/second or watts (W)
Uniform Circular Motion (UCM)
An object moving in a circle at a constant speed is in UCM.
The time it takes for an oject to complete 1 revolution.
Frequency (f) & its unit
- The number of revolutions a ball makes per unit of time.
- revs/sec = hertz
- unit: newton*meter
momentum of an object moving in a circle. Always conserved.
- Vibrational motion = harmonic motion
- An object is in harmonic motion if it follows a repeated path at regular time intervals.
- Ex. Mass on a sring & a pendulum.
Equilibrium Position & Amplitude
- Equilibrium Position: The lowest point in the swing of a pendulum.
- Amplitude: The maximum displacement from equilibrium, measured by the maximum angle or the linear horizontal distance from equilibrium.
- A force that is trying to restore the pendulum back towards the center of the swing.
- Greatest at the amplitude
- Zero as the pendulum passes through the equilibrium position.
- k= spring constant=amount of force needed per unit length (n/m)
- x= the stretched length of the spring
Total Energy = Potential Energy + Kinetic Energy = a constant
- neutron: no charge
- unit: coulomb (c)
- transfer of electrons = transfer of charge
- charge is conserved dring any process
Law of Charges
like charges repel, unlike charges attract.
A device that consists of a metal ball or plate connected to a metal rod with two thin metal leaves attached at the bottom.
The transfer of charge by actual contact.
Magnitude of the electric field
- E=electric field in N/C
- F=force acting on charge q
- =potential difference between points
- A&B in joules/coulombs=volts
- Work we would have to do on a charge to move it against an electric field.
Electric field equation
- unit:volts/meter & newtons/coulomb
- E=electric field
- d=distance between 2 plates
- unit: amperes or amps (coulombs/sec) (i)
- the flow of positive charge through a conductor
- The opposition to the flow of current.
- Measured in ohms .
Ammeter in series with the resistor, it has a low resistance and measures current.
Voltmeter parallel to the resistor, high resistance, measures potential difference.
- the energy used per unit of time.
- unit: watts
the heat in the resistor that is produced when current flows through it.
Joule's Law of heating
- V = voltage
- P = power to the current
- R = resistance
- unit: joule/sec = watt
- charge per unit voltag, depends on the geometry of the plates.
- q= charge on one of the plates
- v= voltage across plates
- unit: coulomb/volt = farad
Capacitance of a capacitator
- A= area of each plate
- d = distance between plates
- Has a battery, resistor, and capacitor in series with one another.
- Can store charge and release it later.
2 rules of Capacitors in RC circuits
- 1) An empty capacitor does not resist the flow of current and thus acts like a wire
- 2) A capacitor that is full of charge will not allow current to flow and thus acts like a broken wire.
- The space around a magnet in which another magnet will feel a force.
- unit: teslas (T)
- -no beginning or end
- -generally point from north to south
Cluster of magnetically aligned atoms.
First right-hand rule
- Place your right thumb in the direction of the current I, and your fingers will curl in the direction of the magnetic field produced by the current.
- In determining the direction of a magnetic field due to the flow of electrons in a wire, use the left hand.
Second Right-hand rule
- Place your fingers in the direction of the magnetic field (north to south) with your thumb in the direction of the current in the wire, and the magnetic force on the wire will come out your palm.
- Use the left hand to find the direction of the magnetic field given electron flow.
Force on a current-carrying wire in a magnetic field
- I = current in the wire
- L = length of the wire in the magnetic field
- = angle between the length of wire and the magnetic field
A charge must be moving across ________ to feel a force.
magnetic field lines
Equation for finding force on a charge moving through a magnetic field
- q= the charge in coulombs
- v= the velocity in m/s
- B = the magnetic field in teslas
- the angle between the velocity and the magnetic field.
moving a magnet through a coil of wire or moving a wire through a magnetic field, and generating a current.
What increases the amount of current produced by the coil?
- 1. Moving the magnet through the coil quickly
- 2. Greater number of coils
The direction of the current induced is (independent or dependent) on the direction in which the magnet or wire is moving?
converts mechanical energy to electrical energy.
A traveling disturbance in a medium that transfers energy from one place to another.
The substance through which a wave moves, such as water for a water wave, or air for a sound wave.
- A vibration of an electric and magnetic field that travels through space at an etremely high speed and does not need a medium through which to travel.
- Ex. Visible light, radio waves, and microwaves.
Waves trasnfer _____ from one place to another.
Two types of Mechanical Waves
Transverse and Longitudinal
Vibrate in a direction that is perpendicular to the direction of motion of the wave.
- Vibrate in a direction that is parallel to the direction of motion of the wave.
- Ex. sound
Properties of Waves
- 1. Period: the time it takes for for a wave to vibrate once
- 2. Frequency: the number of waves that pass through a given point per second
- 3. Amplitude: The maximum displacement of a wave, or its height.
- 4. Wavelength: the length of one complete vibration of a wave
- crest: the highest point on the wave
- trough: the lowest point on the wave
Sound is ____________.
A mechanical longitudinal wave.
Sound Characteristics & Detected as
- Frequency = pitch
- Amplitude = loudness or volume
- Harmonics = Quality or tone
The Doppler effect
- The apparent change in pitch due to relative motion between a sound source and a listener.
- (Moving forward = louder)
- (Moving away = softer)
4 ways to affect a wave
- 1. Reflection
- 2. Refraction
- 3. Diffraction
- 4. Interference
The bouncing of a wave off a barrier.
The Law of Reflection
The angle of incedence of a wave is called the angle of reflection as measured from a line normal (perpendicular) to the barrier. (The wave will bounce off at the same angle it came in)
The bending of a wave due to a change in medium. Ex. a water wave moving from deep water to shallow water will bend its path, slow down, and shorten its wavelength. The wave's speed and wavelength always change in refraction, but not frequency.
The bending of a wave around a barrier. Ex. Water waves bending around a rock in a stream or sound waves bending around the corner of a building. When water waves pass through a narrow opening, the sides of the waves drag on the walls of the opening, causing these parts of the wave to lag behinf the center of the wave and create a semicircular wave pattern.
Constructive Interference & Antinode & In Phase
When two waves are moving toward each other in the same rope and they are on the same side of the rope, they build on each other and create a larger amplitude wave when they occupy the same space at the same time. (constructive interference) the large wave produced by that instant is called an antinode. Waves are in phase when they interfere constructively, after the waves pass through each otehr, they continue moving asif they never interfered.
When two waves are traveling in the same medium at the same time, they _______ with each other.
Two Types of Interference
Constructive & Destructive
Destructive Interference & Node & Out of Phase
If two waves of equal amplitude approach each other on opposite sides of the rope, they interfere destructively; that is, the waves destroy each other for the instant they are occupying the same point of the rope and a node is created at that point. A node is a point of no displacement, in this case resulting in a flat rope. Waves are out of phase when they interfere destructively. Once again, after the waves pass through each other, they continue moving as if they never interfered.
A series of nodes and antinodes.
The speed of electromagnetic waves in a vaccuum is ________.
Refraction (light) & Index of Refraction
- The bending of a light ray due to a change in medium.
- Index of Refraction:
- n = index of refraction
- c = speed of light
- v = speed of light in glass (or other medium)
Short wavelengths to longest
- 1. Red
- 2. Orange
- 3. Yellow
- 4. Green
- 5. Blue
- 6. Violet
Snell's Law of Refraction
- Relates the angles of incidence and refraction.