Physics definitions Flashcards
What is displacement
A measure of the distance but also with a direction
What is mass?
A measure of how much matter makes up an object
What is weight?
The force of gravity pulling an object towards the centre of the planet
What is mass measured in
Kg
What are newtons measured in
N
What is the rule for the extension of a spring
The extension of a spring is directly proportional to the force applied, provided the limit of proportionality is not exceeded
What does the spring constant tell u
How much force is needed to extend a spring by 1 m
The higher the spring the constant the stiffer the spring, true or false
True
8 types of energy
Nucleur
Electromagnetic
Thermal
Kinetic
Elastic
Gravitational potential
Chemical
Vibration
Energy cannot be ? or ?, it can only be ? between different energy stores
Created, destroyed, transferred
Energy can move between energy stores by which 4 different pathways
Mechanical working (force)
Electrical working (circuits)
Heating ( by particles) - conduction and convection
Radiation (light and infrared)
What is work done?
The measure of how much energy is transferred by mechanical working
What is power
The rate at which work is done/ energy is transferred
What is current determined by?
The potential difference across components and the resistance o f the components
The larger the potential difference the ? The current
Higher
The higher the resistance the ? the current
Lower
What are vector quantities
Quantities that have magnitude and direction
What is velocity
Speed in a given direction
In a distance time graph what does a flat horizontal line mean
The object is stationary
In a distance time graph what does a sloping up or sloping down line mean
It means ig is accelerating or decelerating
What does a straight line upwards or downwards mean?
It means the object is moving at a constant speed
In a velocity time graph what does a straight horizontal line mean?
It means the object is moving at a constant speed
In a velocity time graph what does a straight line upwards or downwards mean?
It means the object is accelerating or decelerating
What is acceleration
The rate of change of velocity
Why can the big wherl move at a steady speed and the capsules accelerate at the same times
Because acceleration is the rate of change of velocity and velocity can change not only with speed but also with direction so the capsule can be found at a steady speed but going round changing direction so it is accelerating.
What are the two equations for frequency?
f = v / wavelength
or
f = 1/T
Word and formula equation for force
Force = mass * acceleration
F =ma
Weight equation
Weight = mass * gravitational field strength
W =mg
Work done equation
Work done = force * distance moves
W = Fs
acceleration equation
final velocity - initial velocity / time
(v-u)/t
equation for final velocity squared
Final velocity squared = initial velocity squared + 2* acceleration* displacement
v^2 = u^2 + 2as
kinetic energy equation
kinetic energy = 1/2 *mass * velocity squared
Ek=1/2 mv^2
Elastic potential energy equation.
elastic potential energy = 1/2 * spring constant * extension squared
Ee = 1/2k(esquared)
Gravitational potential energy
Gravitational potential energy = mass * gravitational field strength * height
Gpe = mgh
Power two equations :
Power = energy transferred/ time or
Power = work done/ time :
P =E/t
P=w/t
Force equation
Force = spring constant * extension,
F =Ke
density equation
density = mass/volume
D = m/v
Pressure equation
Pressure = force/area
P = F/A
pressure in fluids
pressure = density *gravitational field strength * depth
P = Dgh
what does Newton’s second law state?
the acceleration of an object is proportional to the resultant force acting on an object
what is the resultant force of an object?
the overall force acting on an object
what does newtons firsy law state
if the forces acting on an object are balanced it will move at a constant velocity
what is the equation for stopping distance
stopping distance = thinking distance + braking distance
when free falling with a weight of 1600N, what is the air resistance after 0 seconds?
0, as there is zero velocity so maximum downwards acceleration
when free falling with a weight of 1600N, what happens to the air resistance as the sky diver continued to fall through the air
the air resistance increased and so does the velocity till about 30 seconds
what happens at 30 seconds with the skydiver when the velocity stops increasing?
the skydiver reaches terminal velocity - where the forces are balanced and is the maximum possible velocity
when opening a parachute what happens to the air resistance and weight
the air resistance is greater than the weight - greater upwards force, so the person decelerates
what happens after the person has firsy opened the parachute?
the air resistance decreases
what factors affect braking distance
condition of brakes, icy and wet roads, tyre wear and the mass of a vehicle
what factors affect thinking distance?
alcohol, drugs tiredness, distractions - phones satnavs, people
what 4 things are key contributors to car safety?
airbags - absorb kinetic energy of the driver, and increased SA for the collision between the car and the driver, seatbelts - absorbs momentum of driver and stops them falling out of windows etc,
crumple zones - cars are designed to crumple on impact therefore protecting people in cars, energy is absorbed,
safety glass - designed to shatter on impact but with larger, less harmful shards
what’s the braking distance
distance taken to stop under the braking force
thinking distance?
how far the car travels from driver seeing hazard and pressing brakes
what equation goes with Newton’s second law?
F=ma
how to find the distance from a speed/time graph -
calculate the area under the graph
what is acceleration
the rate of change of velocity
what is pressure measured in?
Pa - pascals
Solids are tightly ? - compact, vibrate about a fixed ?, have a regular arrangement normally a ?, and have low ?
packed, position, lattice, energy
liquids are close ?, have an ? arrangement, can move past each other to ? the shape of the container,have more ? and can move in different ? at alow speed
togther, irregular, take, energy, directions
gases particles are far ? with almost no forces of ? between particles, are free to move in different ? at high speed and have high ?
apart, attraction, directions, energy
how is atmospheric pressure created?
on a surface by air molecules colliding with the surface
Balloons in a vacuum!! what is the pressure like in the vacuum before it is turned on?
there is an equal amount of pressure inside and outside, and it is equally pushing from outside and inside as Newton’s third law states that every action has an equal and opposite reaction
what happens after the vacuum has been turned on?
there is less pressure outside, More pressure inside which makes the balloon expand
water boiling in a vacuum - what happens before when there is still air?
there is an equal amount of pressure from the air pushing down and the water pushing up so water stays as normal
what happens when air has been removed in the water boiling in a vacuum experiment?
there is less pressure from air since it’s been removed so more pressure from water pushing up and so water starts to boil
what is Boyled law?
as the pressure of a substance increases the volume decreases
what is internal energy?
the sum of all of the kinetic energies and the potential energies of all particles
how can the internal energy be increased?
by increasing the temperature, or by doing work to the system
what is boyles law in equations?
at constant temp p*v is always constant - the same
what does 0K mean?
it means the particles at this temp have close to zero internal energy
what is the definition of specific heat capacity and what is it measured in?
it is the energy needed to raise the temperature of 1kg of a substance by 1 degree, and is measured in J/kg *c
what is the equation for specific heat capacity
E = mc*change in T
what is specific latent heat?
the energy required to change 1kg of a substance from one state to another without changing the temperature
what are the two types of specific latent heat and what are they used for?
specific latent heat of fusion is energy to melt/ freeze,
and specific latent heat of vaporisation is energy to boil/condense
what is the equation for specific latent heat?
E=ml
what is a wave?
an oscillation that moves through a medium
what is a medium?
any type of solid, liquid or gas that has matter
what does a wave transfer? (and what does it NOT?)
it transfers energy, but NOT matter
in a transverse wave what direction are the oscillations compared to the direction of the wave?
the oscillations of the particles are perpendicular to the direction of energy transfer of the wave
in a longitudinal wave what direction are the oscillations compared to the direction of the wave?
the oscillations of the particles are parallel to the direction of the energy wave transfer
what two things do longitudinal waves have?
compressions and rarefactions
on a transverse wave what is the peak?
the top of the wave
on a transverse wave what is the amplitude?
the distance from the equilibrium to peak - max displacement
on a transverse wave what is the trough?
the bottom of the wave
on a transverse wave what is the equilibrium?
a small dashed line in the middle of a wave
what is a ‘p’ wave’s characteristics?
it is longitudinal, so travels a lot faster and can go through liquids and solids!!
what are the characteristics of an ‘s’ wave?
it is transverse, a lot slower and can only go through solids
what can seismic waves do?
be reflected, absorbed, or transmitted/refracted and can also change direction
what are seismic waves used to prove?
the difference in structure and matter of the earths core
if an object travels from a less dense medium to a more dense medium, eg from air to glass what happens to the angle of refraction? does it bend towards or away from the normal?
closer because it is moving faster through the medium
if an object travels from a more dense medium to a less dense medium, eg from water to air what happens to the angle of refraction? does it bend towards or away from the normal
it bends away from the normal as it is moving faster
what are the characteristics of a concave lens?
it only produces a virtual image, is wider at the top and thinner at the middle, is a diverging lens and normally makes the image smaller
what are the characteristics of a convex lens?
can be both virtual and real, so can be projected onto a screen, light is focused in whereas in a concave lens light is reflected out.
in a convex lens what are the characteristics of real images?
they are inverted and if they are drawn before 2F are larger and if they are drawn on 2F are the same size and if they are drawn after 2F they are smaller
what is a real image and what can be done with one?
it is when light rays come together to form an image and it can be projected onto a screen
what is a virtual image
an image where the light rays do not come togther where the image appears to be
what is the equation for magnification?
Magnification = image height / actual object height
what is a focal point?
the area of focus
what is a centre ray?
a ray that passes through the centre of the lens and continues with no change in direction
if someone stands 170m from a cliff and shouts, and head a echo how long will it take for him to hear it given the speed of sound in air is 340m/s
1 second as it will have to travel 340 meters there and back to them
what is the speed of sound in air?
330-340m/s! x
in a closed system the total ? put into the system is equal to the total energy?, this is known as the law of ? of energy
energy, output, conservation
only some of the energy ? is useful, and so the rest of the energy is ? as thermal ?
output, dissipated, energy
Energy is dissipated in all ? changes, and that is stored in less ? ways. friction can result in energy being ? to the ? store of energy of an object, however friction can be reduced with ?
system, useful, dissipated, thermal, lubrication
how can thermal energy also be dissipated? and how can this be reduced?
to the surroundings, can be reduced by use of thermal insulation
TWO differences between sound and EM waves?
sound waves are longitudinal, whereas EM waves are transverse
sound waves CANNOT move through space as it is a vacuum and not a medium whereas EM waves can!!
what is ultrasound and how does it work?
it’s a form of high frequency sound waves that are used to create images between two boundaries and project them (after refracting the image) onto a screen to be seen, these are normally used to scan a baby or foetus
what is ultrasound used to look at and x rays- compare?
ultrasound is used to look at soft tissues, whereas x rays are used to look at bones. ultrasound is used in babies as x rays are also too dangerous because they are ionising radiation.
