P1.3: Pressure Flashcards
What happens when gas particles move about?
Randomly bang into each other and the walls of the container
What do gas particles do when they collide with something?
Exert a force on it
What do multiple gas collisions cause?
A net force on the inside surface of the container
What is pressure?
The force acting per unit area (by the gas)
What happens if you add more air particles to a container than cannot expand?
Pressure increases
How does temperature affect gas pressure?
If the temperature of a gas increases, the gas particles have a higher average speed and collide more frequently
What is the pressure of gas measured in?
Pascals (Pa)
Why does heating increase gas pressure?
Energy is transferred to the kinetic energy store of particles
What happens when the gas is cooled?
Particles have less energy. Particles hit the walls with less force less often so the pressure is reduced
What apparatus is used to measure the pressure of gas?
Manometer
What is absolute zero?
When the pressure reaches 0 Pa
At 0K or -273.14C
What happens to pressure if volume is doubled?
Pressure halves
What happens to pressure if volume is halved?
Pressure doubles
What is the volume and pressure formula? AT ONLY A CONSTANT TEMPERATURE
Pressure (Pa) x Volume (m3) = constant
How can doing work on a gas affect the temperature? Use the example of a bike pump
If you apply force to the pump and move it in you do work on the gas and it gets hotter. The average speed will increase because their kinetic energy increases when they collide with moving piston. Temp increases.
How is atmospheric pressure created?
The weight of the air high in the atmosphere pushes down on the air around us.
Why can’t we feel atmospheric pressure?
Always there
Equal in every direction
Why is the atmospheric pressure lower at higher levels?
If you gain height, there’s less atmosphere above you
What is liquid pressure?
Water molecules colliding against each other other, container and anything else in the water
What happens to liquid pressure as you go deeper into the sea?
Greater pressure on your ear drums
There is a certain limit to the pressure that the human body can withstand
What is the formula for liquid pressure?
Pressure (Pa) = height of column (m) x density of liquid (kg/m3) x gravitational field strength (N/kg)
What will happen if an objects upthrust is equal to its weight?
Object will float
What will happen if a upthrust is less than an objects weight?
Object will sink
What must you do in order to make an object floatable?
You need to make it less dense than the liquid you’re trying to float it on
