Fluid Pressure/ upthrust / atmospheric pressure Flashcards
What is pressure
Force per unit area
How do you calculate the pressure at the surface of a fluid
Pressure = force / area is surface
What does the pressure in a liquid depend on
Depth and density
What is the density in a liquid
It is uniform (same everywhere) and doesn’t vary in shape or size
What happens when an object is submerged in a fluid
The pressure of the fluid exerts a force in every direction
How is upthrust caused
By the resultant force of the object that has been submerged in a fluid
As the force acting on the bottom of the object is larger than the force at the top of the object
What is upthrust equal to
The weight of fluid that has been displaced (pushed out)by the object
When will an object float
If it’s weight = upthrust
Because the forces balance
What is depended on wether or not an object will float
The density of the object
What happens to an object that is denser than the fluid it is placed in
It is unable to displace enough fluid to equal its weight and so the weight is larger than the upthrust at it will therefore sink
How is atmospheric pressure created
By air molecules colliding with the surface on the surfaces of the earth
Where does atmospheric pressure decrease
And why is this
As it gets higher up
As the altitude increase the atmosphere gets less dense and so there are fewer air molecules that are able to collide with the surface
And the weight of the air above it decreases with altitude
