TOPIC 5 SOLIDS, LIQUIDS AND GASES Flashcards
what is the equation for density?
density = mass / volume
what are the units for density ?
grabs per cubic centimetre - g/cm3
or
kilograms per cubic metre - kg/m3
what does it mean if a solid object floats on the surface of a liquid
it has a lower density than the fluid
what does the density depend on?
the density of an object depends on what it’s made of- density doesn’t vary with the shape of size
what does the average density determine
whether the object floats or sinks
what is an experiment to demonstrate density
you can measure the volume by completely immersing the object into a measuring container of water.
the amount the volume reading on the container increases by when you add the object to the water is the volume of the object
this only works for objects denser than water though
what is density?
Density is the mass per unit volume- the measure of compactness of a substance. It relates the mass off a substance to how much space it takes up.
what is the equation for pressure?
pressure = force / area
what is pressure ?
pressure is the force acting per unit area of a surface. Pressure is a measure of the force being applied to the surface of something. It relates how much force is being applied to an object (N) to the area that it is applied over (in m2). Pressure is measured in pascals (Pa) or kilopascals (kPa). 1Pa=1N/m2
describe how pressure works
when force is concentrated on a smaller area creates a larger pressure, but with a larger area, you get a smaller pressure.
describe how pressure works in snowshoes in snow
they have a large surface area and therefore there is less force concentrated into the ground
describe how pressure affects stiletto heels marking floors
there is a small surface area and therefore more force is concentrated into the ground
describe how pressure works when walking on pebbles and sand
even though ther is a small surface area, the individual grains are combined repay her than the individual pebbles, so there is less pressure
how is it possible to lie on a bed of nails
it is possible because the total contact is spread out so there is less pressure applied
convert 1m2 to cm2 and mm2
1m2 = 10,000cm2 = 1,000,000mm2
how do you work out the pressure difference in liquids and gases
pressure difference = height x density x gravity (10)
what is pressure difference for liquids and gases?
pressure in liquids and gases depends on density. It is the difference in pressure between two points in a liquid or gas. It depends on the height difference (m) and the density (kg/m3) of the substance. Gravity also has an affect too - g is the acceleration due to gravity which is about 10m/s2
describe pressure for gases and liquids
in gases and liquids at rest, the pressure at any point acts equally in all directions. in gases and liquids, the pressure increases with depth. The pressure is higher at the bottom of the sea than the surface and it is lower high up in the atmosphere at hand close to earth
describe what happens with a water in a bag with holes
Pressure moves in all directions. It is the same throughout the water so water jets act in all directions. This is because when the water molecules move, they transmit a force to all the molecules next to them.
describe what happens on a diver (bottle experiment description)
the conpression on the bottle increases the pressure in the water. this compresses the air inside the diver. the air now displaces less water so there is less is less upthrust acting on the diver. the diver takes in more water so the weight increases
describe what happens with pressure on a spouting can
as the depth increases, the weight of the water increases so the is more pressure lower down. this increase in pressure which push the water jet out at a greater velocity
why do divers masks not break at great depth
the same pressure and force is Cting inside the mask so the resultant force is 0
describe what happens with atmospheric pressure with a card in a water beaker
the atmospheric pressure pushes up the card and holds water in place. due to the atmospheric pressure being greater than the water.
describe how atmospheric pressure affects a bottle and hot water
after heating, the bottle is full of hot air. as the air cooled, fewer particles collide with the inside of the bottle. this decreases pressure inside the bottle and reduces the density. atmospheric pressure outside the bottle is bigger is bigger so the bottle collapses