Physics A-LEVEL Flashcards
What is a nucleon?
the particles found in the nucleus - protons and neutrons
What is the nucleon number?
number of protons and neutrons
What is the definition of nuclide notation?
shows summary of information about the atomic structure
What is the proton number?
the number of protons in the nucleus
What is the charge of a proton?
+1 (GCSE)<br></br>+1.6x10-19 (A-LEVEL)
What is the mass of a proton?
1.67x10*-27
What is the charge of a neutron?
0
What is the mass of a neutron?
1.67x10*-27
What is the charge of an electron?
-1 (GCSE)<br></br>-1.6x10*-19 (A-LEVEL)
What is an isotope?
Isotopes are atoms of the same element but have the <b>same</b> number of protons but <b>different </b>number of neutrons
What will happen to the proton and nucleon number of an isotope?
- the proton number will stay the same <br></br>-the nucleon number will be different
What is the definition of specific charge?
the ratio of the charge of an ion or subatomic particle to its sub-atomic particle: charge-mass ratio
What is the formula for specific charge?
Specific charge = <b>charge/mass</b>
What is the formula of specific charge (detail)?
specific charge = (+1.6x10-19) <b>x no.protons</b>/(1.67x10-27)<b>x nucleon number</b>
What are the four interactions?
<ul><li>Electromagnetic interaction - causes an attractive and repulsive force between charges</li><li>Gravitational interaction - causes attractive forces between masses</li><li>Strong nuclear interaction - causes attractive and repulsive forces between quarks (so hadrons)</li><li>Weak nuclear interaction - does not cause force however makes particles decay</li></ul>
what type of interaction effects protons and neutrons?
strong nuclear
what type of interaction effects charged particles
electromagnetic
what is the distance between nucleons measured in?
fentometers (fm)
what is 1fm equal to in m?
1x10-15
For strong nuclear force when is it repulsive?
Repulsive at separations of nucleons less than 0.5fm
when is there a strong attraction for the nuclear force?
there is a strong attraction between 0.5fm-3fm
For electromagnetic force when is it always repulsive?
always repulsive from 1fm
what happens during alpha decay?
an alpha particle is released (<b>2 protons + 2 neutrons</b>) from the nucleus as the nucleus is too large for the forces to hold nucleons in place
what effect does alpha decay have on the proton number?
the proton number <b>decreases by two</b>
what effect does alpha decay have on the nucleon number?
nucleon number <b>decreases by 4</b>
what happens during beta-minus decay?
nucleus is unstable and a <b>neutron changes into a proton </b>- a beta particle is <span>released (electron) and an electron anti-neutrino</span>
what is the definition of a photon?
photons are em waves that can only exist in wave packets of energy
what is the equation for energy carried by a photon?
<span>E = hf</span><br></br><ul><li>E = energy (J)</li><li>h = Planck’s constant (Js)</li><li>f = frequency (Hz)</li></ul>
what is another equation for energy carried by photon involving wavelength?
<span>E = hc/wavelength<br></br></span>E = energy (J)<br></br>h = Plancks constant <br></br>c = speed of light (m/s)
what is the value of Plancks constant?
6.63 x10-34
what is the value of speed of light?
3x10*8
what is an electronvolt?
an electronvolt is the amount of energy gained by an electron as it accelerates through a potential difference of 1 volt
how to convert between 1ev to J?
x1.6x10-19
how to convert between J to eV?
divide by 1.6x10-19
what is matter and antimatter?
for every particle there will be its antimatter for example the antimatter of a proton is antiproton
what are the properties of antimatter?
<ul><li>opposite charge</li><li>same mass </li><li>same rest energy</li></ul>
what is the antiparticle of a proton and its charge?
antiproton <br></br>-1
what is the antiparticle of a neutron and its charge?
antineutron<br></br>0
what is the antiparticle of an electron and its charge?
positron<br></br>+1
what is the antiparticle of a neutrino and its charge?
antineutrino<br></br>0
what is the definition of pair production?
when energy is converted into mass you get equal amount of matter and antimatter
what happens during pair production?
a single photon of energy is converted into a particle-antiparticle pair
what happens to the left over energy in pair production?
the leftover energy is converted into kinetic energy (momentum)
what happens during annihilation?
annihilation occurs when a particle and its antiparticle meet and <b>mass is coverted into energy </b>in which the particle and antiparticle are transformed into <b>two photons of energy </b>
why are two photons of energy produced in annihilation?
one photon for rest energy<br></br>one photon for momentum
how is minumum energy calculated?
2 x particle rest energy
what are quarks?
quarks are smaller particles with fractional charge which are contained in protons and neutrons
what does it mean when quarks are fundamental?
fundamental means the quarks are not made of anything smaller
what are the three types of quarks?
d - down<br></br>u - up<br></br>s - strange
what are the three properties might quark will have?
charge <br></br>baryon number <br></br>strangeness
what will the charge, BN and strangeness be for an antiquark?
they will all be the opposite
what is the quark composition of a proton?
uud
what is the quark composition of a neutron?
udd
what are hadrons?
hadrons are a type of particle which are heavy and made from smaller particles
what are the two categories of hadrons?
<ul><li>Baryons - made up of <b>3</b> quarks (or 3 antiquarks)</li><li>Mesons - made of <b>2</b> quarks: <b>one matter and one antimatter</b></li></ul>
what are examples of baryons?
protons and neutrons
what are examples of mesons?
kaons and pions
What is a scalar
A quantity with only magnitude
True
What is a vector
a quantity that has both magnitude and direction
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Scalar example
speed and distance
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vector example
displacement, velocity, acceleration
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What is a moment
The turning effect of a force
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Moment calculation
Moment = force x perpendicular distance from pivot
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What is the principle of moments
sum of clockwise moments = sum of anticlockwise moments
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What is the centre of mass
The point at which the mass of the object may be thought to be concentrated
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How to calculate centre of mass
For a uniform solid it is at its centre<br></br>else you use a plumbob
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What is a couple
A pair of equal and opposite forces acting on an object with different lines of action.
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SUVAT equations
s = ut + 1/2at^2 <br></br>s = (u+v)/2*t <br></br>v = u + at <br></br>v^2 = u^2 + 2as
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What is a distance time graph
A plot of distance against time, the gradient of which is a measure of the object’s speed- the steeper the slope, the greater the speed.
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True
How does a distance time graph work
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What is the gradient of a distance time graph
speed
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Distance time graph of bouncing ball
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What is a velocity time graph
A plot of velocity against time, the gradient of which gives the object’s acceleration. Because velocity is involved, one axis can have negative values.
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How does a velocity time graph work
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Gradient of velocity time graph
acceleration
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area under velocity time graph
displacement
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Velocity time graph of bouncing ball
- Velocity-time graph: <br></br>The velocity graph has two main parts. The first is ALWAYS DECREASING due to gravity’s negative acceleration. The second part is positive and occurs once the ball has hit the ground and is rebounding. <br></br>* The gradient of line line provides the acceleration of the ball. <br></br>* The area idea the graph provides the displacement.
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What is projectile motion
the curved path that an object follows when thrown, launched, or otherwise projected near the surface of Earth
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How to calculate projectile motion
split the values into horizontal and vertical values<br></br>Do SUVAT to get different values
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General rules for projectile motion
Acceleration for vertical is always g<br></br>Time is the same for both v and h<br></br>for vertical v is often 0 (thrown objects that land)<br></br>for horizontal acceleration is often 0<br></br>when an object is thrown up acceleration is -ve
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What is friction
A force that opposes motion
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How to calculate friction
you can use f=ma to get the force and then take off any forces that arent friction
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What is a drag force
the force opposing the motion of an object due to fluid flowing past the object as it moves
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Examples of drag force
Air resistance and friction
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Drag force rules
<div>Are always in the <b>opposite </b>direction to the motion of the object</div>
<div>Never speed an object up or start them moving</div>
<div>Slow down an object or keeps them moving at a constant speed</div>
<div>Convert kinetic energy into heat and sound</div>
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What is lift
force acting on a body in a fluid in a direction perpendicular to the fluid flow
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What affects friction
1) The type of surface<br></br>2) How hard the two surfaces are pressing together
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What is air resistance
the force that opposes the motion of objects through air
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air resistance rule
it increases with the speed of an object
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what other things affect air resistance
Cross-sectional area<br></br>Shape<br></br>Altitude<br></br>Temperature<br></br>Humidity
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How is a plane designed to get less air resistance
stream lined shape
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How does air resistance affect projectile motion
<div>Air resistance decreases the <b>horizontal</b> component of the velocity of a projectileThis means both its range and maximum height is decreased compared to no air resistance</div>
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What is terminal velocity
the greatest velocity a falling object reaches
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How does a falling object reach terminal velocity?
When it first falls the only force acting is it weight<br></br>So the object will accelerate due to gravity and speed up fast<br></br>but air resistance will increase as speed does<br></br>As air resistance the acceleration decreases (f=ma)<br></br>So air resistance eventually becomes equal to weight and the object cannot accelerate as resultant force is 0N<br></br>It has reached terminal velocity
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How is a skydiver opening a parachute represented on a graph
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What is newtons first law
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
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What is Newton’s second law?
Force = mass x acceleration
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What is newtons second law in words
resultant force on an object is equal to its change in momentum
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what is a resultant force
The overall force on a point or object
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How to calculate resultant force
subtract the magnitude of the smaller force from the magnitude of the larger force
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What is newtons third law
For every action there is an equal and opposite reaction
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What does newtons third law mean
<div>It means that every force has a paired equal and opposite force</div>
<div>Newton’s Third Law force pairs must act on two <b>different</b> objects</div>
<div>Newton’s Third Law force pairs must also be of the <b>same type </b>e.g. gravitational or frictional</div>
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Newtons second law equation with momentum
mass x change in v/ time
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What is momentum
The product of an object’s mass and velocity
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What is linear momentum
An object’s mass times its velocity. Measures the amount of motion in a straight line.
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Momentum equation
p=mv
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Is momentum a vector or scalar
vector
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SI unit for momentum
kg m/s
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What is external force
Forces that act on a structure from outside e.g. friction and weight
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What is internal force
forces exchanged by the particles in the system e.g. tension in a string
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What do you call a system that has no external forces
a closed system
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What is the principal of conservation of momentum
The total momentum before a collision = the total momentum after a collision provided no external force acts
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How does the principal work
If you dive of a boat into water, you will move forward but the boat will also move back a bit
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What is force
rate of change of momentum
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Force equation
F= change in momentum/ change in time
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What happens when an objects collides with a wall and stops
It will receive an equal and opposite force from the wall
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How to calculate force of the car after being hit by wall
Work out initial momentum using P=m x v<br></br>Work out final momentum too<br></br>work out change in momentum<br></br>use F=∆p/∆t to get force
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What is impulse
change in momentum
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Impulse equation
impulse = force x time
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Impulse alt equation
I = mass x Final velocity - mass x initial velocity
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When is this equation used
when force is constant
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Impulse unti
Newtons
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How does impulse affect force and time
A small force acting over a long time has the same affect as a large force acting over a short time
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impulse examples
A car having air bags to increase the time it takes for someone to hit their head etc so they experience less of a force
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what is work done
A transfer of energy, as a result of a force acting on an object. If the work is done on an object, it gains energy; if the work is done by an object, it loses energy. The total amount of energy remains the same (it is conserved).
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work done equation
force x distance moved in direction of force
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What is the rate of work equal to
rate of energy transfer
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Power work and time equation
power = work done over time taken
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Power force and velocity equation
P = Fv
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What is efficiency
the ratio of output work to input work
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What is GPE
Gravitational Potential Energy- the energy created by the work done on an object being lifted. It has the potential to do work.
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What is GPE equation
GPE=mgh
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What is kinetic energy
energy of motion
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KE equation
1/2mv^2
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What happens to energy as an object falls
GPE gets transferred into kinetic energy
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What is the conservation of energy
a principle stating that energy cannot be created or destroyed, but can be altered from one form to another.
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