Density and Pressure Flashcards
What is the equation for density?
density = mass/volume
What is the unit for pressure?
pascals (Pa)
What kind of motion do molecules in gas have?
constant random motion at high speeds
What the Brownian Motion known as?
the random motion of tiny particles in a fluid, due to frequent collisions with particles of the fluid
What does the Brownian Motion prove?
it provides evidence that air is made of small particles
What are the two examples of Brownian Motion?
-dust in air
-pollen in water
When gas molecules collide more often or more harder with the sides of a container, how does this effect the pressure?
the pressure becomes higher, hence the higher the force exerted per unit area
How would you calculate the density of an irregular shaped object using direct measurements?
-place the object on a digital balance and note down its mass
-fill the eureka can with water up to a point just below the spout
-place an empty measuring cylinder below its spout
-carefully lower the object into the eureka can
-measure the volume of the displaces water in the measuring cylinder
-repeat these measurements and take an average before calculating the density
How would you calculate the density of a liquid using direct measurements?
-place an empty measuring cylinder on a digital balance and note down the mass
-fill the cylinder with the liquid and note down the volume
-note down the new reading on the digital balance
-repeat these measurements and take an average before calculating the density
What could become an error in calculating density and how could you prevent it?
the measurements of length so you should ensure to take repeat readings and calculate an average to keep this error to a minimum
What is the equation for pressure?
pressure = force/area
What is pressure defined as?
the concentration of a force or the force per unit area
What is an example of increasing the area to reduce the pressure?
tractors have large tyres
this spreads the weight (force) of the tractor over a large area
this reduces the pressure which prevents the heavy tractor from sinking into the mud
What is an example of decreasing the area to increase the pressure?
nails have sharp pointed ends with a very small area
this concentrates the force, creating a large pressure over a small area
this allows the nail to be hammered into a wall
How does pressure in liquids act?
pressure in liquids acts equally in all directions as long as the liquid is not moving
How does pressure in a gas act?
pressure in gases acts equally in all directions as long as the gas is at rest
What is the equation for pressure difference?
pressure difference = height x density x gravitational field strength
What states can the equation for pressure difference be used for?
liquids or gases (provided you known their densities)
