Flashcards
Science
Flashcards do conjunto (64)
- 1What states of matter are considered fluids?liquids & gases
- 2What is cohesion?water is attracted to itself
- 3What is adhesion?water is attracted to other materials
- 4What is surface tension?edge of water acts as skin you have to disturb
- 5What is capillary action?water rising inside small tubes using adhesion + cohesion
- 6What does a molecule of soap generally look like and how does soap affect surface tension?has two sides: water-loving side and water-hating side
Soap affects surface tension b/c soap forces water on edge apart, weakening force - 7What makes something a fluid?flows, changes shape easily
- 8Explain what viscosity is, and why some fluids move slower than others by talking about the way the particles attract/bump into each otherviscosity is how fast/slow a fluid flows
some fluids move slower than others b/c the attraction btw particles are closer together - 9What is density?how close together the particles are
- 10Explain how temperature affects density of solids/liquids/gases.The higher the temperature, the less dense the particles are.
- 11What are units of density?g/cm3, g/ml
- 12If you kjnow the mass is 50 g and the density is 5 g/cm³, what is it's volume?V=m/D=50/5=10 cm³
- 13If 15 g of a substance is 20 cm³, what volume would 45 g of the same substance have?15 g/20 cm³ = 45 g/60 cm³
multiply both terms by 3 - 14What happens if you put different densities together in a container?one with lowest density floats on top one with highest density is on bottom
- 15What is positive/neutral/negative buoyancy and buoyant forces?positive buoyancy: float
neutral buoyancy: suspend
negative buoyancy: sink
buoyancy: upward force by a fluid pushed on an object - 16State the Archimedes Principleyou must displace the same mass of water as you weigh, or else you sink
- 17What is the meniscus of a fluid? How does this cause the “Cheerio effect” we saw in class?meniscus is the curved part of liquid that sticks to edge like adhesion
causes Cheerio effect b/c when it sticks to edge, buoyant force pushes up, and rises to highest point - 18 How does the buoyant force change if you sink lower into a fluid?buoyant force is higher
- 19What causes fluid pressure?random collision of moving particles hitting each other and the walls in all directions
- 20How does your depth in a fluid affect the fluid pressure?as depth goes deeper, fluid pressure is higher
- 21How do barometers work?outside pressure pushes fluid higher in tube until downward pressure from weight of fluid is equal to the upward pressure
- 22How does changing a fluid’s temperature or volume affect the density of a fluid?as temperature/volume increases, fluid is less dense
- 23For a gas trapped in a container, how does changing the temperature of the gas, the density of the gas (by putting more gas in or taking gas out), or changing the volume of the container affects the pressure that gas exerts on the walls of the container?as temperature increases/decreases, pressure is higher/lower
as density increases/decreases, pressure is higher/lower
as volume increases/decreases, pressure is lower/higher - 24How do our lungs use pressure to expand/contract?diaphragm goes down and ribs goes outwards and up so volume increases and pressure decreases, then lungs go outwards and expand, lowering the pressure inside them, lastly outside pressure pushes air down into lungs
- 25Boiling vs evaporatingBoiling: average energy of particles in liquid is high enough to escape cohesion and turn into a gas
Evaporation: at the surface of any liquid at any temperature, a particle can move fats enough to overcome cohesion and escape into a gas - 26What does it mean for a substance to be volatile?molecules that can evaporate easily
- 27What are odorants? How do you make things smell more?Odorants: chemicals that has smells/odors
smells more if it is wet, humid, warmer - 28Why do people’s ears pop?small Eustachian tubes connect your inner ear to your throat to let air in or out to balance the inside & outside pressure
- 29What kinds of fluids are compressible? Why or why not?Gases because the particles are far apart
- 30Give examples of and compare the properties of hydraulic and pneumatic systemshydraulics: incompressible, self=cools, self-lubricates (arteries, veins)
pneumatics: easier to push, compressible, overheats easier (lungs, dentist drills) - 31What is pressure?force of an object pushing on another over a certain area
- 32What is the difference between mass and weight?mass: how much stuff you are made of
weight: how heavy you are - 33What does pressure depend on?height and density of fluid
- 34What is Pascal's Law?pressure on a confined fluid is transmitted in every direction, and acts with equal force on all walls confining the fluids
- 35How do odorants work?Aroma- carrying odorant evaporates
Odorant enters nose, contacts a matching neuron that sends signal to brain - 36Differences between hydraulics and pneumaticsHydraulics: very small spaces between particles; when an external force is applied, only a small decrease takes place in liquid's volume
Pneumatics: very big spaces between particles; particles must be closer in order for force to transmit - 37What do we mean that an object is "more dense" than another?-particles are closer together
- 38Molasses is a thick substance made from sugar cane. It is often used as a sweetener in baking. Why would someone use it instead of sugar water?-if its thick, it is easy to pour/measure
- 39Recommend a way to measure viscosity so that you can compare different fluids.-put fluids in a cup, and see how long it
takes them to pour out - 40What does viscosity depend on?force applied to fluid, shape of particles, space between particles
- 41What does the flow in a tube depend on?pressure difference between ends of fluid, size of tube, material, # of turns
- 42What is the boundary layer?thin layer at edge of fluid that doesn't move
- 43When a liquid is said to be highly viscous it is moving slower or faster than a liquid with low viscosity?moving slowly
- 44How could you decrease the pressure inside a container?-cool the fluid/air
-remove fluid - 45If you suck the air out of a container with a vacuum, what will happen?-air pressure inside will go down, so it will
implode (the pressure outside wins) - 46Compressibility is:-particles are able to get more squished
together - 47Water boils when what happens?-pressure of the water vapour overthrows/beats
the air pressure - 48What affects how smelly something is?-how wet it is, how hot it is (more evaporation)
-how humid it is outside - 49How can we change a sponge’s density?If we let it soak up water, the mass goes up
If we squish it, the volume goes down - 50How can we decrease the pressure we exert on the ground when we step?If we spread out our weight (snowshoe or
lying down), the pressure goes down - 51Why are we lighter in a pool?The buoyant force is pushing up against the
force of gravity - 52What happens when particles are heated up or cooled down?Heated up –particles move faster and expand
Cooled down – particles move slower and
contract - 53What if the object’s volume is difficult to calculate, how could I find its volume?Submerge it in water and measure the
displacement - 54What is a hydrometer for, and how does it work?A floating rod in a fluid; the higher the rod
floats, the more dense the fluid - 55Why does water evaporate faster when wiped around, as opposed to sitting in a puddle?More surface area – more evaporation
- 56Why does water boil at a lower temperature in the mountains?-less air pressure in the mountains makes it
easier for water vapour to beat the air pressure,
so it can do so at a lower temperature - 57Why does viscosity change as you heat a substance?-the particles spread out, and so they flow past
each other faster - 58If an object has a mass of 30 g, what is the gravitational force on it?F = mg = (30)(0.0098) = 0.294 N
- 59If an object displaces 30 ml of water, what is the buoyant force on it?Since it displaces 30 ml of water, that is 30 g of
water (since water is 1 g for 1 ml)
F = mg = (30)(0.0098) = 0.294 N - 60What is the weight of an object that is floating or suspending?weight of 0N
- 61a) An object is suspended in the water. It has a volume of 5 cm3. It must have a mass of ____________ g.a) An object is suspended in the water. It has a volume of 5
cm3. It must have a mass of 5 g (since D = m/v = 5/5 = 1
g/ml -> will be the same as water’s density) - 62b) An object is floating with a volume of 2 cm3. It can have a mass between ____________ g and ____________ g.It can have a mass between 0 g and 2 g (since if it has a
mass greater than 2, the density will be more than 1 g/ml) - 63so the buoyant force must be ____________ N. f) An object has a buoyant force of 25 N and a gravitational force of 146 N, so its weight is ____________ N. g) The mass of an object is 22 g, so its gravitational force is ____________ N. h) An object sinks in water, so its density is between ____________ g/mL and ____________g/mL (a word). i) If an object sinks in water and has a volume of 10 cm3, then it displaces ____________ cm3 of water, and the buoyant force on the object is ____________ N. j) If an object floats in water and has a mass of 4 g, then the object displaces ____________ g of water, which means the buoyant force on the object is ____________ N.e) An object has a weight of 36 N and a gravitational force of 99 N,
so the buoyant force must be 63 N (so that 99 – 63 = 36)
f) An object has a buoyant force of 25 N and a gravitational force of 146 N,
so its weight is 121 N. (since 146 – 25 = 121)
g) The mass of an object is 22 g, so its gravitational force is 0.22 N.
h) An object sinks in water, so its density is
between 1 g/mL and infinite g/mL (a word).
i) If an object sinks in water and has a volume of 10 cm3,
then it displaces 10 cm3 of water, and the
buoyant force on the object is 0.098 N.
j) If an object floats in water and has a mass of 4 g, then
the object displaces 4 g of water,
which means the buoyant force on the object is 0.0392 N. - 64What happens if you seal the lid of a pot?The air & evaporating water is trapped, increasing air pressure, so water must work harder to beat the air pressure