Rotational Motion and Astro Physics Flashcards
The First Differential of Displacement is ……….?
Velocity
Acceleration is the first differential of velocity which means …..?
Acceleration is the 2nd differential of displacement.
Acceleration’s first integral is what?
Velocity
Displacement is the 2nd integral of acceleration which makes it
The first integral of velocity.
The gradient of a curve on a motion-time graph represents what?
Instantaneous rate of change, and can be found by differentiation
The gradient of a curve on a displacement-time graph is what?
The Instantaneous Velocity
the gradient of a curve on a velocity-time graph is what?
The Instantaneous Acceleration
The area under a line graph can be found by what?
Integration
Area under an acceleration-time graph is what?
Change in Velocity
area under a velocity-time graph is what?
The displacement
What must you use when dealing with angular motion?
Radians
How do you convert between degrees and radians
Angle in Radians x 180 degrees/ Pi = Angle in degrees
What force is necessary for an object to maintain circular motion?
Centripetal ( Radial or Central) Force
Centripetal force results in what?
Centripetal (Radial or central) acceleration of the object
an unbalanced torque causes a change in what?
the angular (rotational) motion of an object.
what is the Moment of Inertia?
The moment of Inertia of an object is a measure of that object’s resistance to Angular Acceleration about a given axis.
What is the principle of conservation of Angular Momentum?
The Total Angular Momentum before a collision will equal the total Angular Momentum after a collision, as long as no external torques act upon the system.
How do you convert between Astronomical Units (AU) and metres?
Multiply the number of astronomical Units by the Value given on the data sheet for 1 AU (in metres)
What is gravitational field strength?
gravitational force acting on a unit mass
what is the gravitational potential of a point in space
The work done in moving unit mass from Infinity to that point
the energy required to move mass between two points in a gravitational field is independent of what?
the path taken
What is escape velocity?
The minimum velocity required to allow a mass to Escape a gravitational field to Infinity.
Special relativity deals with motion in what frame of reference?
Inertial or non-accelerating frames of reference.
General Relativity deals with motion in what frame of reference?
non-inertial or accelerating frames of reference.
What is the Equivalence principle?
No experiment can differentiate between the effect of a uniform Gravitational field and an accelerating reference frame. ( Inertial Force and Gravitational force are so similar they are indistinguishable)
Consequences of the Equivalence Principle
Gravity Bends Light
What is spacetime?
a unified representation of three dimensions of space and one dimension of time.
What interpretation does the idea of general relativity lead to?
Mass curves spacetime, and that gravity arises from the curvature of spacetime
Freely moving objects follow what type of path in space time?
A geodesic path, ( path with shortest distance between two points.)
What is the escape velocity of a black hole equal to?
The speed of light.
At the event horizon what appears to freeze.
Time . ( From the perspective of a distant observer)
What is the Schwarzschild Radius
is the radius of the boundary of a black hole. (the Event horizon)
How are stars formed?
They are formed in interstellar clouds, when gravitational forces overcome thermal pressure and cause a molecular cloud to contract until the core becomes hot enough to sustain nuclear fusion, which then provides a thermal pressure that balances the gravitational force.
Stages of a Proton-Proton (p-p) chain
Stage 1 - Two Hydrogen nuclei fuse to form a Deuterium Nucleus, a Positron and an Electron Neutrino.
Stage 2 - A deuterium nucleus and a Hydrogen nucleus fuse to form an unstable Helium Nucleus and A Gamma Ray.
Stage 3 - Two Helium Nuclei fuse to form a stable Helium Nucleus and two hydrogen Nuclei.
Energy is released at all stages in increasing quantities.
A Hertzsprung-Russell (H-R) Diagram shows what?
The classification of Stars
What are the classifications of stars present in a
(H-R) Diagram
Main Sequence, Giant, SuperGiant and White Dwarf.
What type of fusion occurs in main sequence stars
Fusion of Hydrogen occurs in the core.
The mass of a star determines what?
It’s lifetime and Eventual Fate.
Every star ultimately becomes a White Dwarf, A neutron Star or a black hole.
What is one Electron Volt
Is the Work done moving an electron through an electrical potential difference of one volt
What is the apparent brightness of a star?
The energy recieved per unit area from a star, measure in WM-2
What does hydrogen fusion in a star supply?
The Stars outward thermal pressure to balance the inward gravitational forces.
What happens when hydrogen in the core becomes depleted?
Nuclear fusion stops, however gas surrounding the core will still contain hydrogen
Gravitational forces cause both the core, and the surrounding shell of hydrogen to shrink.
the hydrogen shell becomes hot enough for hydrogen fusion to occur.
Leads to an increase in pressure which pushes the surface of the star outwards causing it to cool.
Will be in Giant or Supergiant region of H-R diagram
What happens in the star when the core shrinks enough?
In a star like the sun, the core will become ho enough for the helium in the core to begin fusion.
What is meant by geodesic?
Shortest Distance between 2 points on a curved surface.
What will happen if the universe has ‘greater than critical density’?
Gravitational attraction will overcome expansion . Ending in the Big Crunch
What will happen if the universe has equal to critical density?
Expansion will continue at an ever slowing rate
What will happen if the universe has less than critical density
Expansion will accelerate and end in either the Heat Death or the Big Rip
Is the Big Crunch, expansion. Continuing or the big rip most likely
Big rip is most likely with current observations
The evolution of the universe in the 7 epochs
Inflation - The universe expands at its most rapid, modern physics can’t explain this
Quark epoch - The universe has expanded sufficiently enough to cool to a temperature at which quarks begin to form.
Hadron epoch - the universe has cooled enough for quarks to bind together to form hadrons.
Nuclei epoch - universe has cooled enough for protons and neutrons to bind together to form atomic nuclei. Still too hot for electrons to be bound to nuclei.
Photon epoch- the universe is opaque, filled with plasma of photons, nuclei and electrons
Recombination epoch - cooled enough for electrons to become bound to nuclei, creating first hydrogen atoms. Allows photons to travel freely through space. Universe becomes transparent, comb photons are emitted at this point.
Stelliferous epoch- epoch of stars and galaxies, the current epoch
