6. Further mechanics and thermal physics Flashcards
What conditions are needed for objects to move in circular paths?
An unbalanced force which acts towards the centre of a circular path.
Equation for linear speed?
v = 2πr/T
What is internal energy and how can it be increased?
The sum of the randomly distributed kinetic energies and potential energies of the particles in a body.
It is increased when work is done on it or when energy is transferred to it by heating.
What occurs during a change of state?
The potential energies of the particle ensemble are changing but not the the kinetic energies.
What are the gas laws?
Boyle’s law: when temperature is constant, pressure and volume are inversely proportional pV=k.
Charle’s law: when pressure is constant, volume is proportional to temperature V/T=k.
Pressure law: when volume is constant pressure is proportional to temperature p/T=k.
Can be explained by brownian motion or worked out by pV=nRT
What is absolute zero?
The lowest possible temperature, at which the particles have no kinetic energy, volume, or pressure.
What is the thermal physics equation for work done?
Work done = pressure x Δ volume
What is brownian motion?
The random motion of particles in a fluid caused by collisions with surrounding particles.
It provides evidence for the existence of atoms.
What are the assumptions of our models of particle theory?
-No intermolecular forces act on the molecules.
-The duration of collisions is negligible compared to the time between collisions.
-The motion of molecules is random.
-The particle collisions are elastic.
-The molecules move randomly.
What is a difference between the gas laws and the kinetic theory model?
The gas laws were empirically discovered.
The kinetic theory model arises from theory.
Derivation of pV = 1/3 x Nm(crms)^2:
What is internal energy for an ideal gas?
An ideal gas follows gas laws perfectly, so no other interactions are taking place beyond perfectly elastic collisions between them so they have no potential energy.
The kinetic energy of the atoms.
How has our knowledge and understanding of the behaviours of gases changed over time?
The gas laws were discovered by numerous scientists and later explained by the kinetic theory model.
Knowledge and understanding of any scientific concept changes over time in accordance to the experimental evidence gathered by the scientific community.
