paper 3 Flashcards
What is the diameter of an atom?
1 ✖️10^-10 meters
Why was it named ‘the atom’ ?
Back then was known to be the smallest thing(particle ) in nature
What was dalton’s theory?
🟣🔵🔴🟢🟣🟡🔴🟣
Atoms are tiny INDIVISIBLE particles
All matter was made from atoms
Atoms in an element are identical, different for each element
Billiard ball
What was the cathode ray experiment?
Cathode rays = metal heated up inside a magnetic field
The discovery of electrons
They came from inside the particles (not indivisible)
What was the plum pudding model
Overall a neutral atom:
Random electrons in a
cloud of positive charge- evenly spread throughout
What was the gold foil experiment?
Alpha particles were sent through gold foil
99% passed though
1% of this deflected
What is an alpha particle
2 protons
2 neutrons
What was Rutherford’s model of the atom?
The atom is mostly empty space
The majority of the mass is looted in the nucleus
The nucleus is positively charged
⚛️⚛️⚛️⚛️
What was Bohr model of the atom?
He suggested that atoms move in fixed orbit around the nucleus,
Orbits = electron shellls
What is the size of the nucleus of the atom?
1 ✖️10 **-15 meters
What is orders of magnitude ?
The size relative to the power of (x)
What is density?
A measure of how much matter is contained within a given volume
What is the density formula?
Density = mass➗volume
Kg/m 3 =kg ➗m3
Why are solids more dense than gas?
Particles spread out more and therefore have a higher volume
What is temperature?
A measure of the average kinetic energy of particles in a substance
What is kinetic energy
How fast particles are vibrating/ moving
Measured in J - joules
What are the units of temperature?
*conversion of the two
Kelvin or Celsius
273k = 1 🅾️C
What are physical changes ?
Eg : changes of state & dissolving
No new matter is produced
Particles just arranged differently
Easily reversible
What are chemical changes ?
Eg : burning & chemical reactions
New substances are produced
Difficult to reverse
How do you measure the volume of an irregular object?
Fill the eureka can to the top
Place object in
Make sure the spout is n a measuring beaker
The amount on the beaker is the volume
What is specific heat capacity?
The heat energy required to raise the temperature of 1kg of a substance by 1 kelvin.
A.K.A : how easy or difficult it is to change the temperature of a substance.
The lower SHC means less energy is required
What is the specific heat capacity equation?
E = m ✖️S.H.C✖️temperature change(ø)
J= kg ✖️J/kgk ✖️K / °c
In the S.H.C practical, how could you have it more accurate/efficient?
Put a lid on
Use an insulating container
Add conducting gel between object and container
Submerge the heater fully
What is potential energy?
The energy used to change the position of the particles (changing state - intermolecular bonds)
What is specific latent heat the measure of?
potential energy
What is specific latent heat of fusion?
The heat energy transferred when 1kg of a substance changes from solid to liquid state
(Melting/freezing)
What is the latent heat of vaporisation ?
The heat energy transferred when 1kg of a substance changes from liquid to gas state.
(Evaporating/condensing)
What is the specific latent heat equation?
Energy = mass ✖️S.LH(v/f)
J= kg ✖️j/kg
E=ML
What is the equation for pressure ?
Pressure = force ➗area
Pa = N ➗m^2
How do gases exert pressure?
The particles move in high speed , random directions.
Collision with the walls of the container exerts a force- a net force on the inside of the container (surface) determines the pressure
How does temperature affect pressure?
The more temperature, the faster the particles move, the more frequently the particles collide with the container walls, the more force is exerted resulting in more pressure.
What was Rutherford expecting in his gold foil experiment?
He expected the alpha particles to pass right through as the positive charge was assumed to be spread out
How does temperature affect gas pressure?
As temperature increases particle have more kinetic energy. The particles collide with a greater force at the wall. Leading to a higher resultant force from the wall , leading to higher pressure.
The two are directly proportional as long as volume is constant.
what is the atmospheric pressure on earth?
100 kilo pascals
100,000 pascals
what is the relationship between the pressure and volume of a gas?
pressure and volume are inversely proportional as long as temperature is held constant.
on a graph the line would have a curved L but wouldn’t tough the axis of the graph
what happens to the pressure as the volume is halved?
the particles collide twice as often (as there is twice as less space between the particle and the wall. )
Therefore the force exerted by gas particles per unit of time doubles , doubling the pressure of the gas.
What is the equation for two variables of pressure and volume?
P1✖️V1= P2✖️V2
The product of pressure and volume stays the same before and after a change
What happens when a gas is compressed ?
A force is required to move the gas particles together.
Work= force ✖️distance
Therefore work is done on a gas. The particles gain kinetic energy , move faster, raise in temperature
What happens when a gas is expanded?
The gas particles apply a force, work is done (energy is transferred), the gas particles lose kinetic energy , move slower, a decrease in temperature
What is the earth’s atmosphere and why does it have it?
A layer of gases, near earth due to it’s gravitational field
What happens to the atmospheric pressure as you go higher up and why?
It decreases , because there are fewer gas particles due to it’s weaker gravitational field
Which state of matter has more potential energy?
Gas ,because it has weak intermolecular bonds. This means that a lot of energy has been transferred to it to weaken these bonds
Why is the pressure of a bottle highest at the bottom?
It has a large weight of liquid
How does pressure in a liquid vary with depth?
The pressure in a liquid ONLY depends on the depth below the surface.
More width, more mass of water, more weight, more force
Pressure and depth are directly proportional
How does the density of a liquid affect the pressure?
The higher the density , the more mass, the more weight force, higher force = higher pressure
What is the liquid pressure equation?
Ro GH
Pressure= density ✖️depth✖️gravitational field (10N/m)
Describe up thrust
A force that occurs whenever a body is immersed within a fluid.
Because of a pressure difference between the top and bottom fluid
What is the difference between the atoms and particles?
Particles can be atoms , molecules or ions.
An atom is a single neutral particle
Why do gasses have a low density?
They occupy more volume, as there is more space between the particles, as they have more energy.Resulting in a lower density
How does the depth affect the pressure?
More depth , means more mass, which earns more density, which means more pressure
What is archimedes principle?
The upthrust experienced by a body is equal to the weight of the fluid displaced
What is the formula for upthrust?
*upthrust is the weight of liquid displaced
Force = ro g h a
Force = density ✖️gravitational field strength ✖️height✖️surface area
Upthrust = ρghA
When will a body float, sink and rise
Float:
mg= ρghA
Rise :
Mg<ρghA
Sink:
Mg> ρghA
What happens when the atmospheric pressure is greater inside a ballon that it’s surroundings?
does density of water vary with height ?
NO, trick question . The density of water is constant.
The pressure increases tho
Under what circumstances will a body float?
Under what circumstances will a body sink
In circuit A , the total resistance is less than the smallest resistor value
In circuit B , the total resistance, is an addition of the two values of resistance
where does pressure produce a force?
the net force is produced at right angles to any surface
How many seconds in a hour, how many meters in a mile
3,600s = 1h
1609m = 1 mile
How can a force change an object
It can change the shape or the motion. It can accelerate a body.
Forces are represented with Newtons(Vector’
What is newton’s third Law?
When two bodies interact they exert a force on each other , equality in size but opposite in direction
Give an example of a non contact force
Gravitation field, magnetic, electrostatic
A free body diagram shows
The result force
How do you calculate free bodies in the horizontal and vertical plane?
Pythagoras Theorem , but make sure the diagram is tip to head
To find the direction of the pythagora’s Theron :
Find the degree of the angle using trig.
The angle comes off at the new line and thE largest quantity
How would you resolve a force?
You have to find the horizontal and vertical plane of a diagonal line . You would use trigonometry using the angle and the resultant force. Then do two separate equations to find the two separate values.
Or scale diagram
What is Newton’s first law?
A body will remain at rest on continue at uniform velocity unless acted upon by a resultant force
What is inertia ?
How difficult it is to change the velocity of a body.
The greater mass, the greater interia
What is Newton’s second law?
The acceleration experienced by a body is directly proportional to the resultant force
What is the equation of newton’s 2nd Law
F= M A
N= kg m/s**2
What is magnitude?
The size of something
What is the difference between a scalar and a vector quantity ?
A vector has magnitude and direction whereas a scalar quantity only has magnitude
What is acceleration?
The rate of change of velocity.
If direction or speed changes so does acceleration
V - U
———
T
Why is a body moving in a circle at constant speed have a resultant force?
It’s changing direction and therefore velocity, constantly accelerating which means (N’s 1st law) there is a resultant force.
This resultant force is known as centripetal force
What is terminal velocity?
Constant velocity , zero resultant force
Describe a parachuter’s journey
- Weight acts down, no a lot of drag, RF increases down, acceleration, increasing velocity
- Air resistance increases to the point where RF is zero, terminal velocity - no acceleration & constant velocity
- Remains until parachute is opened, SA increases, increasing drag. RF is acting upwards, decreasing velocity
- As velocity decrease so does drag so eventually the RF becomes zero again, terminal velocity 2, contact velocity, zero acceleration
Define momentum
How difficult it is to stop a moving body. The two factors affecting this are mass and velocities.
(A vector value)
How do you calculate momentum? 🅿️
Mass * velocity = momentum
Kg * m/s = kg m/s
What is the law of conservation of momentum?
The total momentum before an event is equal to the total momentum after an event .
How do you apply the LofM when two stationary bodies push and move away from each other?
Eg (explosion)
The total momentum before and after must equal zero , as they were stationary.
To calculate a total:
. Calculate the first object using P = mv
. Then calculate the second object by knowing the fact the Momentum is negative, to equal zero, as they were going in opposite directions
How do you use the L of C when two bodies collide and move off together?
Calculate the total before , by calculating each separate component’s momentum and adding them together.
Calculate the total after but appreciate it as one value , use the momentum of previous to find out other variables
What is work?
The transfer of energy .
Whenever a force acts upon an object, work is done
What is the work equation?
Work done = force * distance
J = N *m
What happens in term of energy when work is done?
Energy is transferred from one form to another.
Eg : kinetic to gravitational potential energy,
When a body is lifted
What is power?
The rate of energy transfer
What is the power equation?
P = E/T
W= J / s
How do you calculate the gravitational force?
Gravitational force = mass * gravitational field strength
N = kg * (N/ kg)
The gravitational field strength is always 10 N/kg on earth
What is the kinetic energy formula?
Kinetic energy = 0.5 ✖️mass ✖️ (speed2)
J =. Kg* (m/s)2
E= 1/2 mc squared
What is the potential energy formula?
Potential energy = mass * height * gravitational field strength
J = kg * m * (N / kg)
U=mgh
What is an elastic body?
Objects that return to their original shape when the deforming force is removed
What is the deforming force?
Stretching , compressing or bending a body to change the shape
What is a plastic body?
Objects that do not return to their original shape when the deforming force is removed
What body is a spring?
Elastic, as they are designed to return to their original position. However if too large of a force is applied they will break.
What is Hookes Law?
The extension of a body is directly proportional to the force applied as long as the limit of proportionality is not exceeded
What is the equation for Hooke’s Law
Force exerted by spring = K✖️extension
N = (N/m) ✖️m
How do you find the extension?
New length - original length
What is the spring constant a measure of?
How stiff the material is.
The larger the konstant ,the stiffer it is
😖
What assumption is made when calculating Hooke’s Law
The limit of proportionality has not yet been reached
On a force Extension graph what is the gradient?
The spring constant
What does a diagonal line show on a Force Extension Graph?
That it obeys Hooke’s law
What does point X show on the graph?
The limit of proportionality, the point just before the line starts to curve
What is the gradient of a distance time graph ?
Speed
What does a steeping curve mean on a DT graph?
Velocity is increasing = acceleration
What does a levelling off curve mean on a DT graph?
Decreasing velocity = deceleration
How do you find the gradient of a curved line?
Create a tangent
Where does the reaction force act
From point of contact in the opposite direction
Where does weight act?
Always vertically downwards from the centre of the object
Who would reach the floor first If two people with a different mass jump of a building at the same time?
They would both reach at the same time.
Because F=MA
A=F➗M
F= mass✖️gravitational field (10N/m)
A=(mass✖️gravitational field (10N/m))➗mass
A= gravitational field
A= 10 same for both
What is formula for moment’s?
M= d ✖️force
d is the perpendicular distance from the pivot to the the line of action of force (m)
What is the principle of moments?
The sum of the clockwise moments about any point = the sum of anti clockwise moments about any points
*nothing is turning
What is mechanical advantage?
The number of times a machine multiplies the effort force
*how easier it makes it for you ( to apply less force)
Load(F1)➗effort(F2)
What it the mechanical advantage of gears?
Output cog radius➗input cog radius
Largest value always as the numerator
What happens to a car when travelling up hill? (Gears)
🟢you change to a lower gear
🟢the means input gear is a small gear is connected to a larger gear
🟢a input larger moment
🟢an output smaller moment
🟢causing the wheel to turn more slowly
*Large mechanical advantage
What happens when a car is travelling down hill?
🟢you change to a high gear
🟢the means input gear is a large gear is connected to a smaller gear
🟢a input smaller moment
🟢an output larger moment
🟢causing the wheel to turn more fast
*Large mechanical advantage
How do hydraulic machines work?
(Brakes)
Diagram
🔵use the pressure exerted in liquids to multiply forces and apply them at distance
Which distance would be applicable ?
What is the velocity time graph for a bouncing ball?
What is the velocity time graph for a bouncing ball?
Part a
Part b
Part c
What way do electric field lines go?
(electrostatic)
Leave positive and enter negative
Positive is the long wire, negative is the short
What is current?
The rate of flow of charge, how many electrons pass a point in a second
What is the formula for current?
I = Q➗ T
I= amps
Q= coulombs
T= seconds
What is the symbol for a diode?
A circle with a triangle , line at the end pointing in the direction of current
What is the symbol for an LEd
The symbol of a diode with two arrows coming out of the circle
What is the symbol for a fixed resistor?
A solid rectangle
What is the symbol for a variable resistor, what does it do?
A solid rectangle with an arrow going diagonally though
Vary the resistance, and the current and p.d
What is the symbol of a fuse?
A rectangle with a line going through
What is the symbol for a heater?
A solid rectangle cut into boxes
What is the equation for potential difference? (Energy)
V = W➗Q
V= potential difference ,v
W= work done, J
Q= charge , C
What pattern do fixed resistors follow on an IV graph
🔺Diagonal straight line (linear circuit element) - resistance is constantly
🔺Ohmic conductors (follows Ohm’s law)
Describe the IV graph for a filament light bulb
🔺The resistance increases with p.d
🔺As the resistance increases as it is getting hotter
🔺Non - linear circuit element
Describe the IV graph for a diode
Forwards resistance is low
Reverse resistance is high
describe the relationship between current and resistance
describe the relationship between temperature and resistance
Mention how it impacts current
Describe magnet
An object with a magnetic field
Exert a force on a magnetic material
Describe the look of magnetic fields exist around wires?
Concentric rings
The space between the lines increases with increasing distance
How does a stronger current affect the magnetic field?
Stronger magnetic field
the space between the lines are smaller
What is a solenoid?
A device that increases the strength of the magnetic field around a current carrying wire
What does an electric motor consist of?
A loop of wire , with a current in a magnetic field
Why must the current be reversed every half turn?
If the current was not reversed , the direction would be (force).
Causing it to spin anti clockwise and then clockwise,
Shaking and flopping -not turning
State Lenz’s Law
The direction of the induced p.d is such that it opposes the change producing it
Describe the alternator
*generator affect
Produced a.c (magnetic field lines as cut from above and below
Uses a slip ring(doesn’t change direction of the current)
Describe a dynamo
*generator effect
Produces d.c
Split ring (reverses the current every half turn)
How do you increase the induced p.d of an alternator?
🟣rotate coil faster (more field lines cut per second)
🟣stronger magnetic field (field lines closer together, so more cut)
🟣more coils
* doubling frequency
Compare dynamos and alternators
How do transformers work?
Describe the difference between step up and step down transformers
What is the transformer equation?
How do microphones work?
🟢generator effect
🟢sound waves hit diaphragm, causing it to move forwards and backwards
🟢so the coil attached also moves backwards and forwards
🟢the coil moves inside a magnetic field , so cuts field lines perpendicularly
🟢a p.d is now induced within coil, producing an electrical signal fed to a speaker
How do loudspeakers work?
🟢a current carrying wire, enters a magnetic field . MOTOR EFFECT. This causes the wire to experience a force
🟢as the coil moves forwards and backwards, the diaphragm moves forwards and backwards
🟢therefore creating sound waves , at the same frequency diaphragm vibrates
Describe the circular magnet
In loudspeakers,
The charge
Draw the magnetic field around a solenoid
