Module 3 - Density and Pressure Flashcards
What is meant density
The mass of a body per unit volume
What is the SI unit for density
Kg/m³
What is the equation for density
Density = mass/volume
What is the density of water
1000 kg/m³
How do you convert between cm³ and m³
Multiply by (0.01)³
How do you find the volume of regular objects
- Spheres: V = (4
/3)πr³
Rectangles: b x h x w (using vernier calipers) - Cylinders: h x πr^2
How do you find the volume of irregular objects
The object can be placed in water inside a measuring
cylinder. The change in volume when the object is fully submerged is equal to the volume of
the object.
What is meant by pressure
The normal force exerted per unit cross-sectional area
What are the SI and SI base units for pressure
Pascals - (Pa)
SI Base: N/m-2
What is the equation for pressure
Pressure = Force/Area
What is Archimedes Principle
The upthrust exerted on a body immersed in fluid, whether partially or
fully submerged, is equal to the weight of the fluid that the body displaces.
What are the factors that affect the Pressure exerted within a fluid
1- The Depth
2 - The Density of the fluid
3 - The Gravitation Field Strength
Why does the depth of the water affect the pressure
There is a greater overall force pushing downwards due to above particles
Why does the density of the fluid affect the pressure
The heavier the fluid, the bigger the force pushing down on the body submerged in the water of the water
Why does the Gravitational Field Strength affect the pressure
The stringer the pull of gravity the more the fluid weighs and the greater the force exerted on the submerged body
What is the equation for the pressure in fluids
P = ρgh
Derive the equation for the pressure in fluid
- Pressure at base = weight of column / cross-sectional area
- The mass of fluid in the column equals density x volume
- as the height of the column is equal to the column’s
volume divided by its cross-sectional area, h = V/A, this
can be substituted in to produce P = ρgh
Why is upthrust generated in a fluid
- Due to pressure differences between the top and bottom of the object within the fluid
What is the equation for upthrust
Upthrust = mass of the fluid displaced x gravitational field strength
Derive the equation for upthrust from F = PA and P = hpg
Force at the top of the surface: hpgA
Force at the bottom of the surface: (h + x)pgA
resultant upwards force = (h + x)pgA - hpgA = xpgA
