aim of physics
to understand the physical laws and principles that influence every aspect of daily life
displacement of an object
the distance
... [Show More] that an object is from some starting point, and is measured in units of length
How does displacement change when an object is in motion?
it is constantly changing
How is motion described?
by displacement, velocity (speed) and acceleration
speed
distance traveled by an object per unit of time
speed = (distance traveled/time)
velocity
speed in a given direction
What two things does velocity tell us about a moving object?
its speed and direction
acceleration
the rate of change in velocity; can be any change in velocity, either positive or negative.
deceleration
negative acceleration or a decrease in velocity and can change in direction
How is acceleration calculated?
(final velocity-original velocity)/time
Why can velocity and acceleration be described using vectors?
because they have both magnitude and direction
What quality do all moving objects have?
momentum; an object traveling at a specific velocity has momentum
calculate momentum
Momentum = mass x velocity
conservation of momentum
the total movement of an isolated system is always constant, ie during a collision, the momentum of each body changes but the total momentum is conserved. One object may lose momentum, but this momentum is gained by other object
How is momentum conserved when a moving object hits a stable object, such as a bullet hitting a wall?
the moving object, like the bullet, delivers an impulse to the wall, and this impulse is said to be the change in the objects momentum
Newton's first law
objects in motion tend to stay in motion and objects at rest tend to stay at rest
inertia
the property of matter that resists any change in motion
Newton's second law
describes the relationship between force, mass and acceleration; the force of an object equals the mass of the object times its acceleration
f = ma
newton
the unit that represents a force that accelerates a mass of 1 kg 1 meter per second
friction
force that is exerted on an object along a surface or whenever an object has a velocity along a surface and the two surfaces touch
gravity
the force of attraction between all objects in the universe
what determines the weight of an object?
the pull of gravity on an object
Why is the Earth's gravitational force great?
because the Earth has a large mass
Is the force due to gravity and the acceleration of an object towards earth the same?
the force due to gravity is not the same on every object and depends upon the object's mass, and the acceleration toward earth is the same for all objects, independent of their mass
How does a change in the force of gravity change an objects weight and mass?
it changes the object's weight but not its mass
density
d=m/v
What is torque and what does it measure?
the perpendicular force times the lever arm; the ability of a force that is applied perpendicularly to rotate an object around an axis, ie using a wrench to turn a bolt
What is centripetal force?
continual force on an object pulling it towards the center of the circle
What does Newton's third law state?
that for every action there is an equal and opposite reaction
What is energy?
the ability to do work?
What are the two types of energy?
1. Kinetic energy
2. Potential energy
Describe kinetic energy?
energy associated with motion, any moving body has this energy because it is able to do work by moving other bodies; tells us how much work body can do by moving other bodies until it is brought to rest
How do you calculate kinetic energy?
kinetic energy = 0.5( mass x velocity)^2
What is potential energy?
the energy stored in a body because of its position, has more potential energy at the top of a hill than at the bottom
What is work?
the product of the force applied to an object and the distance through which the force is applied
How do you calculate work?
work = force x distance
What is a joule?
the unit of energy equal to the work done by a force of 1 newton acting over a distance of 1 meter
What is power?
the rate at which work is done
What is the formula for power?
power = (force x distance)/ time = work/time
What is a machine?
a device that makes work easier by changing the force or the direction of an applied force
What is the efficiency of a machine?
the work done divided by the energy used to power the machine
Why can't a machine ever be 100% efficient?
because of friction
What are the six simple machines?
1. inclined plane-slanted surface used to raise an object
2. wedge-moving inclined plane
3. screw-inclined plane wrapped around a cylinder
4. lever-simple machine that is free to move around a fulcrum when force is applied
5. pulley-chain or rope wrapped around a wheel
6. wheel and axle-level that rotates in circle
What is a compound machine?
two or more simple machines
What is an atom?
smallest particles of an element that retain all chemical properties of an element
What is the kinetic theory of matter
atoms in matter are in a constant state of motion
What are the three ordinary states of matter, and in which states are molecules free to move around?
1. gas
2. liquid
3. solid
free to move around in liquid and gas states
Where does pressure come from?
it results from the impulses from the collision of molecules with the walls of the container
What does Boyle's Law state?
the volume of a fixed amount of gas varies inversely with the pressure of the gas. If volume of gas is decreased both the number of particle collisions and the pressure of the gas increase. If volume increases, pressure decreases
What does Charles' law state?
defines the relationship between the temperature and volume of of a gas. Volume of a fixed amount of gas varies directly with its temperature. If the temperature increases, the volume increases
What is temperature?
a measure of the average kinetic energy of the particles in a substance; tells how warm or cold a substance is with regards to other substances
What does temperature determine?
whether a substance gains or gives up heat when put into contact with other bodies.
What is heat?
a form of energy that causes the particles of matter to move faster and farther apart
What is the specific heat of a substance?
the heat needed to raise the temperature of 1 gram by 1 degree.
What is is a phase change?
the physical change of a substance from state to another
What is latent heat?
the heat energy needed per unit mass to change the phase of a substance
What is the ice point?
the temperature at which ice melts or water freezes F 32 C 0
What is the steam point?
the point at which water at standard pressure boils C 100 F 212
What is the triple point?
point on the Kelvin scale where water exists simultaneously as a gass, a liquid and a solid.
What is absolute zero?
the lowest possible temperature on the Kelvin scale.
What is motion?
a change in position relative to a frame of reference
What is a wave?
a rhythmic disturbance that travels through matter or space
What does wave motion accomplish?
a means of transferring energy
What are the two types of waves?
transverse waves and longitudinal
What is a transverse wave?
a wave in which matter vibrates at right angles to the direction in which the wave travels, ie waves on the ocean
What is a longitudinal wave?
a wave in which matter vibrates back and forth along the path that the waves, ie sound waves
What is periodic motion?
motion that repeats itself over and over again, such as the motion of a pendulum
What is a periodic wave?
a motion that repeats itself at regular intervals and that transfers energy but not mass
What is a period?
the time it takes for motion in a periodic wave to repeat itself and is measured in seconds
What is a cycle in periodic motion?
one complete repetition of a periodic event
What does a frequency of a wave tell us?
how often a cycle repeats itself in a specific time unit
How is frequency often measured?
in Hertz (Hz) which is equivalent to cycles per second
What is amplitude?
refers to the maximum distance a wave rises or falls as it travels, and it is related to the energy that the wave carries
What is amplitude related to in sound and light?
Brightness for light, loudness for sound
What is the crest of the transverse wave?
the maximum upward displacement
What is the trough of a transverse wave?
maximum downward displacement
What is the wavelength of a transverse wave?
the distance between two successive crests
What is the wave speed of a transverse wave?
the frequency of a wave times the wavelength
What is diffraction?
the bending of lightwaves around an obstacle
What happens when two waves meet?
they combine and form a new lightwave
What is interference of a wave?
how the two waves interact whith each other when they go through the same portion of a medium at the same time
What is resonance?
when the vibration of one system results in vibration of the other system of the same frequency
What are photons?
streams of tiny packets of energy
What determines what kind of light wave is produced?
the amount of energy in the photons
Why are light rays called electromagnetic waves?
because the moving photons generate electric and magnetic fields
What is the electromagnetic spectrum?
the complete spectrum of light, arranged in order of their wavelengths
What is visible light?
the portion of the electromagnetic spectrum that is visible to the human eye
What types of waves make up the electromagnetic spectrum?
radio waves
infrared waves
visible light
ultraviolet rays
x-rays
gamma rays
What type of waves are sound waves?
longitudinal waves, vibrate in the direction of their motion
What part of the sound wave determines pitch?
frequency
What determines the loudness of a sound?
amplitude
When does the doppler effect occur?
whenever there is relative motion between the source of waves and the observer
What does reflection mean with regard to sound waves?
when a light wave bounces off a surface and does not absorb its energy
What is refraction?
the bendig of light rays as they pass from one medium to another; happens because light moves at different speeds through different mediums
What is dispersion?
the separation of light into its component colors
What is a lens?
any transparent material that refracts light
What is a convex lens?
thicker in the center than it is at the edges
What happens when parallel rays of light pass through a convex lens?
they converge or bend towards the center, creating a focal point
What is a focal point?
the point at which light rays meet after passing through the convex lens
What is a concave lens?
a lens that is thicker at the edges than it is in the middle
What hapepns to light rays when they pass through a concave lens?
they diverge because they are bent towards the edges
What is Coulomb's law?
like forces repel each other and unlike forces attract each other. The electric force between two charges is proportional to the product of two charges [Show Less]