5th Form Topics After Transformers Flashcards
What is the Big Bang theory?
13.8 million years ago the universe began to expand and exploded outwards
The motion is still seen with distant galaxies
What is the steady state theory?
Proposes the universe has always existed in a similar state to today
Universe is constantly growing - has no beginning or end
What is the galaxy movement?
The expansion of space causes galaxies to appear to be moving apart
The space in between galaxies is what is growing
This can be explained by Hubbles law
What is redshift?
As space expands light waves get stretched out so their wavelengths shift
The colour of their waves shifts to the red end of the spectrum
What theory does redshift support?
Both steady state and big bang
What did Hubble observe?
Light emitted from distant galaxies is redder than expected, which indicates these galaxies are accelerating away from the Milky Way
The further the galaxy from earth, the greater the redshift
Further from earth, the faster each galaxy is moving
Supports the universe expanding
What does CMBR stand for?
Cosmic
Microwave
Background
Radiation
What is CMBR?
Protons and electrons combined to produce neutral hydrogen atoms which radiated light
The wavelength of these were shifted to the microwave region as the universe cooled and expanded
We can detect microwave radiation throughout the universe today
What theory does CMBR support?
Big bang
Can solids or liquids be compressed or squashed?
No
What is a fluid?
A gas or a liquid
What is the particle theory?
Gases consist of very small particles which constantly move in random direction
Particles collide with one another and the walls of the container
An increase in temperature = an increase in kinetic energy
What is temperature in gas (K) proportional to?
The average kinetic energy of its particles
What is Brownian motion?
Particles in a fluid move randomly
Because they are bombarded by other moving particles
Larger particles are moved by the lighter faster moving molecules
What is absolute zero?
The coldest temperature at -273 degrees Celsius
These particles have as little energy as they can get
How do you convert from Kelvin to degrees?
Subtract 273
How do you get from degrees to kelvin?
Add 273
What are the ideal gas molecule laws?
They are in a constant state of random motion
Higher temperature = higher kinetic energy
T is proportional to the kinetic energy, but not speed
There is no loss of energy during collisions (elastic)
No forces of attraction between particles
Volume of a particle is insignificant compared to the volume of the container it is in
What is boyles law?
For a fixed mass of gas at a constant temperature, the product of pressure and volume is a constant
What is the pressure law?
For a fixed mass of gas at a constant volume, pressure is directly proportional to its absolute temperature
To work out pressure what do you first have to do?
Make sure the temperature is in kelvin
What is the definition of elastic behaviour?
If a material returns to its original size and shape when you remove the forces stretching or deforming it, it is demonstrating elastic behaviour
What is plastic behaviour?
If the material stays deformed after the forces are removed
What is the amount a spring stretches proportional to?
Amount of force applied to it
What is the spring constant?
Measures how stiff a spring is (the larger the spring constant, the stiffer the spring is)
What is the elastic limit?
When the object stops obeying hookes law
When does an object accelerate?
If the speed changes
The direction changes
Or both the speed and direction change
What is an objects acceleration if it’s falling due to gravity?
10m/s2
When does an object accelerate?
If the speed changes
The direction changes
Or both speed and direction change
What is momentum?
A measure of how strongly something is moving
What is an elastic collision?
If kinetic energy before equals kinetic energy after
What is an Inelastic collision?
If kinetic energy before does not equal the kinetic energy after
If objects collide and move apart what type of collision is it?
Elastic
If objects collide and move together what type of collision is it?
Inelastic
What is the rate of change of momentum equal to?
The force applied
What is the impulse of a force?
F∆T
What is an impulse?
A vector quantity with the same direction as force
What is an explosion?
The initial momentum is zero
The outgoing pieces then move out in opposite directions so momentum is conserved
What reduces the force?
The rate of change of momentum
How does a seat belt help reduce force?
It stretches
This reduces the rate of change of momentum
So reduces the force on the passenger
How does a crumple zone work?
The material squashes in a way to reduce the momentum of the car over a period of time
How do air bags work?
They reduce momentum more slowly to zero therefore reducing the forcwe
What is the centre of mass?
Is the point about which its mass can be considered to act
What is a lamina?
A 2D objects which is flat and whose thickness we can ignore
What is stable equilibrium?
Returns to equilibrium position when slightly displaced
What is unstable equilibrium?
Neither returns to same equilibrium or status in place when displaced slightly
What is neutral equilibrium?
Remains displaced position when disturbed
What is a moment?
The turning effect of a force around a fixed point called a pivot
What is the principle of moments?
Sum of the clockwise moments = sum of the anticlockwise moments
What is the conservation of momentum?
Total momentum before = total momentum after
