pressure in liquids and gases Flashcards
1
Q
what is a fluid
A
a substance that can flow- they are either a liquid or gas
2
Q
what happens when particles collide with a surface
A
they exert a force at right angles (normal) to the surface
3
Q
what is pressure
A
the force acting per square metre on a surface
4
Q
what is the unit for pressure
A
pascal
5
Q
what does pressure increase in a liquid with
A
it increases with the depth of the liquid
6
Q
why does pressure increase with the depth of a liquid
A
because
- the pressure at any point in a liquid is due to the weight of the liquid above that point
- the weight of a liquid depends on its density
7
Q
what is atmospheric pressure caused by and when does it decrease
A
air molecules colliding with surfaces , this decreases as height above a surface increases
and the density of the atmosphere decreases with air molecules so there are fewer air molecules per cubic metre
