11.1 Distance + displacement

  1. The motion of an object looks different to observers in different frame of reference.– ex) I’m watching my friend running on the street in my car. – my frame of reference is my car
  2. The SI unit for measuring distance = meter(m)
  3. The direction and length of a straight line from the starting pt to the ending pt of an object’s motion is displacement
  4. Displacement and velocity are examples of vectors b/c they have both magnitude and direction.
  5. The sum of two or more vectors is called the vector resultant.

11.2 Speed + velocity

  1. Speed is measured in units of m/s.
  2. A car’s speedometer measures instantaneous speed.
  3. is the equation that defines average speed
  4. A constant slope on a distance-speed graph indicates constant speed.
  5. A difference between speed and velocity is that velocity indicates the direction of motion and speed does not.
  6. A distance-time graph indicates an object moves 20km in 2h. The average speed of the object is 20km ÷2h = 10km/h.
  7. Because its direction is always changing, an object moving in a circular path experiences a constant change in velocity.
  8. two or more velocities add by vector addition.

11.3 Acceleration

  1. A moving object does not accelerate if its velocity remains constant. (accelerate = gets faster or slower –negative acceleration = slowing down)
  2. Freely falling objects accelerate at 9.8m/s2 b/c of force of gravity of the earth acts on them.
  3. The velocity of an object moving in a straight line changes at a constant rate when the object is experiencing constant acceleration.
  4. The acceleration of a moving object is calculated by dividing the change in velocity by the time over which the change occurs.
  1. Accelerated motion is represented by curved line on a distance-time graph.
  2. A car that increases its speed from 20km/h to 100km/h undergoes positive acceleration.
  3. Instantaneous acceleration is how fast a velocity is changing at a specific instant.

Know the graphs of constant speed and constant acceleration (my study guide 11.3)

12.1 Forces

  1. A push or pull is an ex. of an force
  2. The type of force measured by a grocery store spring scale is weight.
  3. The sum of all the forces acting on an object is called the net force
  4. If the forces acting on an object produce a net force of zero, the forces are called balanced forces.(-no net force  no change in motion)
  5. The force that opposes the motion of objects that touch as they move pass each other is called friction. (depends on weight of the object, types of surface ex), bigger weight, rough surface  greater friction)
  6. It usually takes more force to start an object sliding than it does to keep an object sliding b/c static friction is usually greater than sliding friction.
  7. The two forces acting on a falling object are gravity and air resistance.
  8. When a falling object reaches terminal velocity, the net force acting on it is zero.
  9. The drag force acting on falling sky diver is also known as air resistance.
  10. The pathof motion of a thrown javelin is an example of projectile motion.

12.2 Newton’s 1st + 2nd laws of motion

  1. The tendency of an object to resist any change in its motion is called inertia.
  2. During a head-on auto collision, inertia causes a passenger the front seat to continue moving forward.
  3. The acceleration of an object is equal to the net force acting on the object divided by the object’s mass. Force(N) = mass(kg) ×acceleration (m/s2)
  4. The force of gravity acting on an object is the object’s weight.(gravity = attractive force between 2 masses)

12.3 Newton’s 3rd Law and momentum

  1. If a golf ball and bowling ball are rolling at the same speed, the bowling ball has greater momentum. P (momentum:kg-m/s)= mass(kg) ×velocity (m/s)
  2. When you push on a wall, the wall pushes back on you. (Newton’s 3rd Law – action-reaction)
  3. In a closed system, the loss of momentum of one object is equal to the gain in momentum of another object.

12.4 Universal forces

  1. The observation that a charged object can attract or repel other charged object led scientists to conclude that there are 2 types of charges.
  2. The universal force that is most effect over the longest distance is gravity (gravitational force)
  3. The centripetal force acting on the moon continuously changes the direction of the moon’s motion.

13.1 Fluid pressure

  1. Pressure is the result of force distributed over an area.
  2. The formula, , is used to calculate pressure.
  3. The SI unit of pressure is the pascal (Pa).
  4. A pascal, the SI unit of pressure, is equal to 1 newton per m2. (pascal (Pa)=N/m2)
  5. a substance that flows and assumes the shape of its container is a fluid.
  6. As a liquid is added to a beaker, the pressure exerted by the liquid on the bottom of the beaker increases. (depth/height increases  pressure increases)
  7. The pressure exerted by a fluid at any given depth is exerted equally in all directions.
  8. As your altitude increases, air pressure decreases.

13.2 Forces and pressure in fluids

  1. A hydraulic jack is an application of Pascal’s principle. (pressure gets evenly/equally distributed in fluids)
  2. A device that uses pressurized fluids acting on pistons of different sizes to change a force is called hydraulic system.(using Pascal’s principle)
  3. As the speed of a fluid increases, the pressure within the fluid decreases. (Bernouilli’s principle) – airplane wing shape using Bernouilli’s principle  lift
  4. In a hydraulic lift system, the fluid pressure exerted throughout the system is same.
  5. The downward force produced when air flows over the winglike spoiler on a race car is an example of Bernouilli’s principle.

13.3 Buoyancy

  1. The apparent loss of weight of an object in a fluid is called buoyancy.
  2. The direction of the buoyant force on an object placed in a fluid is upward.
  3. Even a rock at the bottom of a lake has buoyant force acting upward on it.
  4. The unit g/cm3 is often used to express density.
  5. As you climb a high mountain, the buoyant force exerted on you by the atmosphere decreases. (density of the atmosphere decreases.)
  6. A submerged submarine alters its density to rise or fall in the water.
  7. The weight of an object that sinks in a fluid is greater than the buoyant force acting on it.

14.1 Work + power

  1. For work to be done on an object, the object has to move.
  2. Any part of a force that does not act in the direction of an object’s motion does no work on an object.
  3. The SI unit of work is the joule.
  4. You calculate work by multiplying the force acting in the direction of motion by the distance of the object moves. Force(N) W = F*d (directions of force + moving distance should be parallel)

1N x 1m = 1N-m = 1J

(direction of force exerted parallel to the direction of the movement)

  1. The rate at which work is done is called power.
  2. The SI unit of power is watt (W). : watt=J/s
  3. The watt and the horsepower are both units of power.

14.2 Work + Machines– machines do same work

  1. A machine is a device that changes a force.
  2. A device that changes the size or direction of force used to do work is called machine.(usually decreases force by increasing distance)
  3. The force that is exerted on a machine is called the input(effort) force.
  4. Besides a reduction in friction, the only way to increases the amount of work output of a machine is to increase the work input.

14.3 Mechanical Advantage + Efficiency

  1. The mechanical advantage of a machine is the number of times that themachine increase the input force.
  1. The mechanical efficiency of any machine is always less than 100%.

14.4 Simple machines

  1. A screw can be described as an inclined plane wrapped around a cylinder.
  2. The fulcrum is always between the effort force and the resistance force in a first-class lever.
  3. The bottle opener is a second-class lever. (fulcrum-output force – input force)
  4. The IMA (ideal mechanical advantage) of a third-class lever is always less than 1. (effort arm < resistance arm)
  5. As the thickness of a wedge of given length increases, its IMA decreases. (b/c effort distance shortens)
  6. Two or more simple machines working together make up a compound machine.
  7. A watch consists of a complex system of gears. Each gear acts as a continuous lever.

Know all 6 machines + 3classes of lever, difference between fixed pulley and moving pulley. (see my study guide of 14.4)

15.1 Energy + its forms

  1. Energy of an object increases when work is done on the object.
  2. Energy + work are measured in the SI uni called joule (J).
  3. If the mass of an object doubles, its kinetic energy doubles. KE=1/2 mv2
  4. The kinetic energy of an object is proportional to the square of its velocity.
  5. Energy that is stored due to position or shape is called potential energy.
  6. When a pole-vaulter flexes the pole, the pole-vaulter increases the pole’s elastic potential energy. (15.2)
  7. You can calculate an object’s gravitational potential energy by using the equation, PEg=mgh(mass(kg) × 9.8m/s2 × height(m)
  8. Mechanical energy does not include thermal energy or chemical energy.
  9. The sum of the kinetic energy and potential energy of an object is called mechanical energy.
  10. All energy can be considered as kinetic energy, potential energy, or the energy in fields.

15.2 Energy conversion + conservation

  1. Wind turbines convert kinetic energy into electrical energy.
  2. The process of changing ene4rgy from one form to another is called energy conversion.
  3. “Energy cannot be created or destroyed” is a statement of the law of conservation of energy.
  4. When an apple falls from a tree to the ground, the apples’ beginning kinetic energy (0 b/c no velocity) and ending gravitational potential energy (0 b/c no height) is both equal to zero
  5. the kinetic energy of the pendulum bob decreases between locations 1 2

If you rollerblade on a hill, at the top you have only PE at the enf of the hill you have only KE

  1. In the equation E=mc2, c is the speed of light.

15.3 Energy resources

  1. Energy resources that exist in limited amount and, once used cannot be replace except over the course of millions of years are called unrenewable energy resources.
  2. Flat collector plates through which water flows are found in active solar energy systems.
  3. Geothermal energy, in addition to being renewable, offers the benefit of being non polluting.
  4. Turning off unused lights or appliances is an ex. of energy conservation.

16.1 Thermal energy + matter+16.2

  1. A measure of how hot or cold an object is compared to a reference pt can be measured in units of temperature or average kinetic energy of particles of the object.
  2. Heat is the transfer of thermal energy b/c a temperature difference.
  3. a hot dinner plate has higher thermal energy than a similar dinner plate at room temperature.
  4. ~
  5. If the temperature change of an aluminum nail is negative, thermal energy is transferred from the nail to the surroundings.
  6. In a calorimeter, the increase in the thermal energy of the water and the decrease in the thermal energy of the sample are equal.
  7. The transfer of thermal energy with no transfer of matter is conduction. (radiation)
  8. The transfer of energy as waves moving through space is called radiation. (sun heat E = infrared waves – 18.2 = only possible transfer of heat in vacuum
  9. The type of thermal energy transfer in fluids is convection.
  10. As an object’s temperature increases, the rate at which it radiates energy increases.
  11. The thermos in the fig 16-1 has 2 insulators – glass layers and the vacuum. The vacuum is the better thermal insulator. (good conductor – metal (b/c of free e- + compact particles); good insulator – wood, Styrofoam – not dense, space bt/ particles)
  12. The material that conducts thermal energy well is called a thermal conductor.
  13. The study of the conversion between heat and other forms of energy is called thermodynamics.
  14. Thermal energy that is not converted into work by a heat engine is called waste heat.
  15. The statement that absolute zero cannot be reached is known as third law of thermodynamics.
  16. In most automobile engines, the linear motion of the strokes is turned into rotary/circular motion.
  17. A steam-heating system is most similar to hot-water heating system.
  18. In a hot-water system, room temperature is controlled by a device called a thermostat.
  19. as the fluid in a pump evaporates, heat is transferred from the surrounds to the fluid.
  20. Having air cleaned as it passes through fileters near the furnace is an advantage of an air-forced system.

16.3 Heat engines =convert heat E into work (mechanical E)

Refrigerator – refrigerant vaporizes (liquidgas) and absorbs heat (from food); then condenses (gasliquid) and releases heat to the outside

Internal combustion engine – 4 steps (intake  compression  power  exhaust)

17.1 Mechanical waves – waves = traveling disturbances that carries E

  1. You can make a wave in a rope by adding energy (shake) at one end of the rope.
  2. Instead of crests and troughs, as in an ocean wave, a longitudinal wave has compressions and rarefactions.(compression=molecules of medium close each other; rarefactions = molecules of medium apart from each other)
  3. The crest of a traverse wave is most similar to a compression in a longitudinal wave. (crest=maximum displacement upward of medium particles)
  4. A wave in a rope is a traverse wave, but a sound wave is a longitudinal wave.
  5. Waves in a rope are transverse waves because the medium’s vibration is perpendicular to the direction in which the wave travels. (cf. longitudinal w = parallel to the direction of wave)
  6. A pebble drops straight down into a tub of water, setting surface waves that travel between the water and air.
  7. In a transverse wave, wavelength is measured from crest to crest or from trough to trough.
  8. To determine the speed of a wave, you must know the wave’s wavelength and frequency.

17.2 Properties of mechanical waves

  1. If a wave has a wavelength of 2m and a frequency of 3.0 hertz, its speed is 6m/s. (speed = frequency × wavelength) ; (period x frequency =1)
  2. To compare the energy of different waves, measure the amplitude of the waves.
  3. Amplitude measures the greatest displacement of a wave from the rest point/position.

17.3 Behaviors of waves(reflection, refraction, constructive/destructive interferences, standing waves)

  1. A wave entering a new medium at an angle will undergo refraction as one end of the wave changes speed.
  2. Ocean waves will not bend if they approach the shore at the right angle.
  3. If two waves collide and form a temporary larger wave, the interference is constructive. (crest/trough at same position  2 amplitudes add up.)
  4. At the nodes of a standing wave, there is no displacement from the rest position. (standing waves seem to be not moving, nodes and antinodes alternating)

17.4 Sound + hearing(sound = longitudinal waves)

  1. The standard measure used to compare sound intensities is the decibal (dB). – increase 10dB  10times louder; increase 40db  104 louder
  2. When a person plucks a guitar string, the number of half wavelengths that fit into the length of the string determines the pitch of the sound produced.
  3. On a piano, striking strings with the hammers sets up vibrations between the strings and the soundboard.
  4. When a train streaks by blowing its whistle, the changing pitch you hear is due to the Doppler Effect. (sound approaches  pitch increases; sound goes away  pitch goes down)
  5. The part of the ear that collects sound waves and focuses them inward is the outer ear.

Infrasound (frequency lower than S) S(sounds audible to human ears) ultrasound (frequency higher than S)

Speed of sound (V) higher in medium w/ compact particles (Vsteel>Vwater>Vair)

18 Electromagnetic spectrum + light

Light= particles (photoelectric effect: e- changes w/ metal only with blue light not with red light b/c Eblue light>Ered light

Light = waves (Thomas Young’s experiment) – refracts

Electromagnetic spectrum – all electromagnetic w arranged in order of frequency/wavelength – gamma rays (highest freq – shortest λ; radio waves (lowest freq – longest λ)

  1. Electromagnetic waves are transverse waves consisting of changing electric and magnetic fields.(18.1)
  2. Warm objects give off more infrared radiation than cool objects give off. (18.1)
  3. The speed of light ina vacuum is 3×108m/s. (18.1)
  4. The farther away you are from a light source, the less intense it is.(18.1)
  5. Objects that scatter some of the light that is transmitted through them are translucent. (18.3)
  6. When viewed in a red light, an object that reflects all the colors of light will appear white. (18.4)
  7. Combining equal amounts of the three pr8imary pigments produces black. (18.4)
  8. Electromagnetic waves can travel through a vacuum. (18.1)
  9. Light is produced when electrons change energy levels in an atom. (18.1)
  10. Visible light waves have a shorter wavelength than infrared waves have(18.2)
  11. A transparent objecttransmits almost all of the light that strikes it. (18.3)
  12. The electromagnetic waves with the shortest wavelengths are gamma rays. (18.2)
  13. An ultraviolet light wave has a wavelength of 300nm and a frequency of 7.0×1014 Hz. The ultraviolet light is not traveling through a vacuum. (18.2) (b/c (300×10-9)m ×(7.0 ×1014)Hz = 2100×105m/s = 2.1 ×108m/s (speed of light slower than 3×108m/s)
  14. In a microwave cooking, the food is heated in water and fat molecules in the areas near the surface of the food than in the center. (18.2)
  15. A mirage, or distorted image, can be caused by the refraction of light as it moves into layers of hotter and hotter air. (18.3)
  16. White light passing through a prism separates into colors b/c of the differences in the wavelengths of each color of light. (18.4)
  17. The electromagnetic waves shown in Figure 18-1 are an example of amplitude modulation used in certain radio broadcasts. (18.2)
  18. Light amplification by stimulated emission of radiation is known as laser light.
  19. To form white light from the combination of only two colors of light, the colors must be complementary. (18.4) – know primary colors of lights/pigments
  20. The following electromagnetic waves are arranged in order of increasing frequency: infrared, visible lights, ultraviolet. (18.2)

Polarization of light - sunglasses

Luminous object: (18.5) – visible ; source of light – ex) sun

Illuminated object: (18.5) – visible; light reflected - ex) moon

Transparent (see through – light passes through in the same direction)-translucent (light goes through but in random directions  fuzzy image)– opaque (light absorbed- can’t see through) (18.3)

Prism – speed of light slows down in glass  different colors (18.4)

Know virtual/real image

19.1 Mirrors

  1. The law of reflection states that the angle of reflection is equal to the angle of incidence.
  2. The angles of incidence and reflection are the angles that rays make relative to a line drawn perpendicular to surface of a mirror. (normal line)
  3. The image that appears to be behind a plane mirror is a virtual image.
  4. The mirror in figure 19-1 is a concave mirror.
  5. The type of image that can be projected on a screen is a real image.
  6. Mirrors that curve outward and away from the center are called convex mirrors.
  7. A bowl-shape that could hold water can be described as having a concave shape.

19.2 Lenses(know index of refraction)