density / pressure Flashcards
mass is measured using
an electronic balance
- zero it
- use on a level surface
measure volume
regular = cross section area x length
irregular - displacement method
- put in eureka can and measure displacement (at eye level, bottom of meniscus on level surface)
pressure in solids
force spreading out over a large area reduces pressure
mass - weigh on electronic balance
convert to force using W = mg
find area
calculate pressure
how to measure diameter
use callipers to find diameter
or ruler and set squares
repeat in diff places and average
how to measure irregular shape
on a squared piece of paper draw shape and count squares
pressure in liquids
increases with depth as there is a greater weight of water above you
this is why dams are thicker at bottom
pressure is same at all points of the same depth (depends on depth not shape of container)
liquid pressure experiment
fill cylinder and block holes then release and draw diagram of path water takes out holes
ml > cm^3
1 ml = 1 cm^3
why not accurate
parallax error
not on flat surface
not read at meniscus
set to zero
most precise
smallest volume and increments (smallest resolution)
how to find density
- calculate mass on electronic balance
- calculate volume
- use p = m/v
- repeat and average
what to control - density
temp
as temp changes so does density
pressure measured in
N/m^2 / pascals (Pa)
or N/cm^2
why balloon increases in size (bell jar)
- gas pressure inside the balloon is greater than outside (no air outside)
- hence the pressure difference causes balloon to expand
why ballooons move together when air blown between them
- pressure inbetween is lower than pressure either side
- because faster air has less pressure
- pressure difference means they move together
