Creation to collapse Physics

These are my notes still got two chapters to cover. Linked to the edexcel specification.

Includes thermal,Oscillations,Astrophysics and cosmology  

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  • Created by: Shivani
  • Created on: 13-04-12 14:14
Preview of Creation to collapse Physics

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Unit 5 ­Physics from
creation to collapse
Thermal energy
Investigate recognise and use the expression E=mc
Specific heat capacity is the quantity of energy needed to raise
the temperature of material, per kilogram per degree rise in
temperature.
Specific heat capacity can be calculated using this equation
E
c = mT , Giving the c the units J kg-1K -1
Measuring specific heat capacity:
1. Weigh a block of aluminium to find its mass m and then
place it in the lagging.
2. Add a small amount of cooking oil to ensure good thermal
contact when the heater and thermometer and inserted
3. Take the initial temperature of the block. Switch on the
power supply and start the stopwatch record the current and
potential difference
4. After three minutes switch of the power supply and record
the highest steady temperature reached.
5. You can than find the specific heat capacity using the
equation I V t = mc(f - i)
Explain the concept of internal energy as the random distribution
of potential and kinetic energy amongst molecules
In gas the molecules have Kinetic energy due to their random
motion. In addition molecules that are made from two or more
atoms have kinetic energy due to rotation and vibration.

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In an ideal gas the internal energy is entirely the random kinetic
energy of its molecules
Ideal gas assumptions:
1. The intermolecular forces are negligible except in collision
2. That the collisions between molecules and with the wall are
elastic
3. Just before a collision molecules have kinetic energy the
closer the molecules get the larger the repulsive force so
K.E is transferred to potential energy as a result of work
being done to overcome resistive force so the molecule is
temporarily stationary
4.…read more

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C 2 > is the mean squared and can calculated by squaring all the
speeds and divide by the number of speeds.
T is temperature measured in Kelvin
1
2 m < c2 > is the average Kinetic energy of a molecule
The average Kinetic energy of molecules is proportional to the
absolute temperature of the gas
Use the expression pV = NkT as the equation of state for an
ideal gas
N is the number of molecules of gas
k= 1.…read more

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Oscillations
Recall that the condition for simple harmonic motion is F = kx,
and hence identify situations in which simple harmonic motion
will occur
In oscillation the motion is repetitive about a fixed position with the
object at rest at either extremes and has maximum speed at
midpoint
For an oscillation the force acting on the oscillating body and
therefore its acceleration must be proportional to the
displacement
The force and therefore acceleration always act in opposite
directions towards the equilibrium position
F =- kx…read more

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Plot a graph of F against X the graph should be a straight line and
the gradient will be the spring constant
Finding the spring constant using simple harmonic motion
Set up apparatus similar to that for the previous experiment.
This time measure the time taken for the masses to make 10
oscillations
To help judge the start and stop of an oscillations put a marker at
the centre of an oscillation, e.g.…read more

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Obtain a displacement ­ time graph for an oscillating object and
recognise that the gradient at a point gives the velocity at that
point.
A card is attached to masses to give a good reflective surface.
Data logger set to record for 10 seconds at a sampling rate of
100 per second.
Computer can be programed to give graphs of displacement,
velocity and acceleration against time.
Rotary sensor
A pendulum is connected to a rotary sensor.…read more

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At either extremes the Kinetic energy is 0 and G.P.…read more

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The heavy dense bob is pulled back and released
This pendulum will oscillate at it natural frequency f o ,
determined by its length and given by the equation
T = 2 gl
All other light pendulums are coupled to this diver pendulum
by a string so they will experience a forced oscillation = in
frequency to that of the driving pendulum
Pendulums closer to the driving pendulum absorb more
energy because there natural frequency is closer to the
natural frequency of the driving pendulum.…read more

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Latest technology is to coat turbine blades with ductile material. (A
material that can be plastically deformed without fracture) which
means that it can absorb a lot of energy.
If a ductile material feels vibrations it goes through hysteresis
loops each vibration.
Astrophysics and cosmology
Use the expression F = Gm1m2/r2
Newton proposed that every particle in the universe attracts every
other particle with the Force F.…read more

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Recall similarities and differences between electric and
gravitational fields
Gravitational effects Electrostatic effects
Field strength
F F
g=m E=Q
(GPE) (EPE)
P.d.…read more

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