P.1.3 Flashcards
Gas pressure why?
Increase particles then
Increase temp then
Gas particles collide with the inside surface, and exert a normal force to the surface, which adds up to produce a net force/ an area = pressure
1) more volume , then pressure increases, as they collide with walls more entering more pressure
2) increase temp then particles gain energy in kinetic store, meaning they move around more quick with more force, meaning more collisions that are harder exerting mor pressure. But volume has to be fixed
At constant temperature what happens
PV= constant, because pressure is inverses
E yproportional to volume , so when volume decrease, pressure increase, therefor pressure= k/v, Pv= k
When would wpressure by 0 pa
Decrease temperature, means particles have less energy and pressure decrease . Pressure temp is proportional, and extrapolating graph shows at 0k, absolute 0 which is -273° then it 0
What happens when work is done on the gas, so (when you decrease the volume)
Work done against gas makes the temperature rise, and work done by gas makes temp drop. This because temp = average speed of kinetic energy of particles, which increase when work is done as energy is transferred to kinetic energy stored and so sometimes you let it settle for a bit before investigations the relationship between pressure and volume
Pressure increase volume?
Volume of container may change if container can move
Pressure out and in ballon
Ballon expand when pressure in is more then out. It stops when pressures the same., so expand increase volume meaning pressure decrease and =
Atmospheric pressure
As you go up what happens
100kpa at sea level REMEMBER
Atmospheric pressure decreases as you go up. This because the pressure is the weight of the air (massx gravity) of above it pushing down, as you go higher, there is less mass and thus weight.
Sensory if wir also affects the atmoosheric oressure , more dense at sea level because weight compresses it, and less dense at top. Assume density uniform tho
Liquidpressure
Remmeber in calculations for TOTAL pressures to add atmospheric too.
Pressure liquid = density x gravity strength x depth
Pressure increases with depth as it experiences the weight of the water particles above it
Pressure at bottom of an object higher then oressure at top, always because if depth, so bottle squirt more water bottom
Upthrust
When object submerged into water, there is a differenc of pressures at the bottom of the object and top, creating an overal resultant force upwards (pressur = fierce / area, force = pressure x area, therefore resultant). This is called up thrust
For float the uothrust = weight if force,
If upthrust > weight , then it moves upwards until they equal
If uothrust < weight, sinks
In upthrust, the SIZE IF UPTHRUST IS = TO THE WEIGHT IF WATER IT DISOLACES, so for it to be=, it must displace the same wiegst of water if the ibject and float
Less dense means less weight, so if less dense object placed in water, less uothrust needed to displace weight = to its weight, and it floats
Same density of water = just floats underneath, as uothrust = weight displaced
More dense then water object, object can’t displace our thirst = to its own weight, therefore weight if object greater then uothrust so sinks
