Prelim Revision Flashcards
Spontaneous nuclear fission
A large atomic nucleus splits into two nuclei of smaller mass number plus several free neutrons, releasing energy.
Stimulated nuclear fission
A large atomic nucleus is induced by bombarding it with neutrons, it splits into two nuclei of smaller mass number plus several free neutrons, releasing energy.
Nuclear fusion
In nuclear fusion, two small atomic nuclei combine to form a larger nucleus, releasing energy.
CMBR
As the universe expanded it has cooled but we should be able to find some heat energy remaining.
Vertical velocity…
Is always -9.8
Weight acting down a slope:
Fparallel=mgsinθ
Weight acting normal to slope:
Fperpendicular=mgcosθ
Random uncertainty:
max value – min value/number of values
Impulse
The sudden force acting on an object for a short interval of time.
As time of contact increases, the impulse decreases.
Change in momentum.
Can be calculated using area under Ft graph.
How to find displacement
Area under velocity time graph
Horizontal velocity
Vh=vcosθ
Vertical velocity
Vv=vsinθ
Conservation of energy
v=√2gh
Momentum when stick
m1u1+m2u2=mv
Momentum when no stick
m1u1+m2u2=m1v1+m2v2
Impulse
The time of contact during a collision.
A short time of contact means a larger force.
Can find impulse using the area under the Ft graph.
Change in momentum
(∆ P)
∆P=mv-mu
Ft=∆P
Inelastic collision:
When KINETIC energy is not conserved.
Calculate total kinetic energy before and after.
Elastic collision:
When KINETIC energy is conserved.
Calculate total kinetic energy before and after.
Stellar objects radiation
Emit more radiation the hotter they are.
Emit radiation over a wide range of frequencies.
Momentum eqn
P=mv
t=1/Ho
Dark matter
Undetectable matter believed to be responsible for gravity.
Dark energy
Causes the expansion of the universe to accelerte.
What is beta decay evidence for?
Neutrinos
Quarks
up,charm,top +2/3
down,strange,bottom -1/3
Leptons
Electron,muon,tau -1
Corresponding neutrino 0
Antiparticles
All particles have them.
Same mass, different charge.
When particle & antiparticle collide they destroy each other producing energy.
Hadrons
Heavy particles made of groups of quarks.
Baryons - 3 quarks
Mesons - 2 quarks
- Quark and antiquark
Bosons
Graviton: Infinite range, weakest.
Photon: Electromagnetic, Infinite range, holds electrons in atoms.
Gluon: Holds protons together, strongest force, very short range.
Work done in electric fields
Change in electrical potential energy.
Linear accelerator
Accelerated in a vacuum pipe.
Adv. Simple acceleration
Disadv. Must be very long.
Cyclotron
Start at centre.
Electrodes called dees accelerate particles by moving from one dee to another.
When it reaches edge its extracted.
Synchrotron
Circular linear accelerator.
Magnets used to keep charged particles in the centre of the accelerator due to walls being very cold and could affect the acceleration rate if touched.
CERN.
Threshold frequency
Each metal has a different fo.
When f>fo electrons are ejected with kinetic energy.
