Our Dynamic Universe Flashcards
List of scalar and vector quantities
Scalars:
Speed, Distance, Mass, Time, Temperature
Vectors:
Velocity, Displacement, Acceleration, Force, Momentum
Steps to answering a projectiles question
- Calculate Uv and Uh using v cos theta = Uh and v sin theta = Uv
- Find maximum height using v² = u² + 2as
- Find how long it took to travel the full distance using v = u + at, then multiply the time by 2
- Find out how far it went horizontally using s = vt
Forces in a lift
Heavier - accelerating upwards, decelerating downwards
Lighter - Accelerating downwards, decelerating upwards
Forces down a slope
down the slope - mg sin theta
directly down - mg
force going into the slope - mg cos theta
friction = force down the slope if object is moving at a constant speed
What is terminal velocity
It’s when the air resistance equals the weight of a free falling object, the forces are balanced and the object is now falling at a constant velocity.
Collisions between masses
Inelastic - momentum is conserved, total energy is conserved, but kinetic energy is less (decreases)
Elastic - All three factors are conserved
Explosion -momentum is conserved, total energy is conserved, but kinetic energy is more (increases)
Momentum equations
P = mv
m1 u1 + m2 u2 = m1 v1 + m2 v2
Law of conservation of momentum meaning momentum before = momentum after but only if no external forces are applied.
Impulse equation
Ft = mv - mu
P = the area under the Ft graph
What is time dilation
If someone is travelling at a speed close to the speed of light in a vacuum, they will experience less time than someone stationary on earth as they are in there own frame of reference. T dash is larger
What is length contraction
A person on a space craft travelling at a speed close to the speed of light will measure the spacecraft to be the actual length of it whereas someone measuring it from earth will measure a smaller value. L dash is smaller
What is the Doppler effect?
When the frequency of a moving source changes for observers. When the source is moving away, the frequency is lower (wavelength increases +) and when it is moving towards you, it is higher (wavelength decreases -)
What is redshift
Redshift = frequency decreasing, wavelength increase so source is moving away Blueshift = frequency increasing, wavelength decreases so source is moving closer
What is hubbles law
It is the evidence that the universe is expanding from a single point, as the further a galaxy move away, the faster they go
Age of the universe?
1 divided by hubbles constant
Stellar objects
hotter objects have a smaller peak wavelength
hotter objects emit more radiation per unit surface area
What is CMBR
CMBR is the cosmic microwave background radiation which is more evidence for the big bang theory. It is the radiation from the young universe which has stretched as the universe has expanded
What is olbers paradox
It is not day time all the time because the light from distant stars are dimmed cause they are red shifting from the observer and are too distant to create enough light to make it day
What is dark matter
It is a mass that is said to make up the rest of the universe as galaxies and stars were measured to be a certain mass but the actual mass was larger and was unknown why, so dark matter was the solution.
what is dark energy
It is the evidence for the increasing rate of the expansion of the universe as it is said to be the thing accelerating galaxies away from each other. Cannot be observed but can be measured and is siad to make up 74% of the universe.
