Flashcards in physics paper 2 - solids liquids and gases Deck (33):
density is measured in?
g/cm^3 or kg/m^3 1g/cm^3 = 1000kg/m^3
what does the average density of an abject determine?
whether it floats or sinks
how will a solid object float?
if it has a lower density than the fluid
how come you measure the volume of an oddly shaped solid?
completely immersing it in a measuring container of water- the volume difference- only works for objects denser than water
pressure is measured in?
the same force applied over a larger area creates?
a lower rpessure
in gases and liquids at rest, how does the pressure act on all points?
equally in all directions
in gases and liquids how does the pressure increase?
pressure difference is the?
the pressure between two points in a liquid or gas
height x density x g
1000 000 cm^3
what does particle theory say?
that gases consist of very small particles which are constantly moving in completely random directions. the particles hardly take up any space
they constantly collide with each other and with the walls of their container
if you increase the temperature of the gas you give its particles more energy
what happens as you heat up a gas?
the average speed of its particles increases- has kinetic energy
what is brownian motion?
the zig-zag random motion of particles in a liquid
large heavy particles can be moved with Brownian motion by smaller, lighter particles travelling at high speeds
what is absolute zero
the coldest anything can get =-273 degrees- atoms have as little KE as possible
it's the start of the kelvin scale -273 degrees= 0Kelvin
to convert degrees celcius to kelvins
to convert kelvins to degrees celcius
how do particles create pressure?
when they collide with something, they exert a force on it and their momentum and direction change. In a sealed container gas particle smash against the container's walls-creating an outward pressure- depends on how fast the particles are going and how often they hit the walls
how does heating a gas increase the pressure?
the particles move faster and have more KE so hit container's walls harder and more often creating more pressure- temp in K and pressure are proportional- Double the temp= double the pressure
same amount of gas in bigger container?
pressure will decrease as fewer collisions between the gas particles and the container's walls
pressure x volume =
at a constant temp what is the pressure?
how are solids held together?
strong forces of attraction hold the particles close together in a fixed, regular arrangement. the particles don't have much energy so they can only vibrate about their fixed positions
how are liquids in their state?
weaker forces of attraction between the particles. they are close together but can pass each other and form irregular arrangements. they have more energy than those in a solid. move in random directions at low speeds
how are gases in their state?
almost no forces of attraction between the particles. the particles have more energy than those in liquids and solids- free to move and travel in straight lines in random directions at high speeds
what is evaporation?
when particles escape from a liquid and become gas particles. particles can evaporate from a liquid at temperatures that are much lower than the liquid's boiling point
when can particles near the surface of a liquid escape?
1) the particles are travelling in the right direction
2) the particles are travelling fast enough to overcome the attractive forces of the other particles in the liquid
what happens to the particles in the liquid when the fastest particles evaporate?
the average speed and KE of the remaining particles decreases
what does the decrease in average particle energy mean?
the temperature of the remaining liquid falls and the liquid cools
what happens if you double the temperature in kelvins?
the average kinetic energy of the particles double- the temperature of a gas in K is proportional to the average kinetic energy of its particles