Wa3 topics Flashcards
How do you calculate pressure?
P=F/A
What can a force do to an object?
*move from a state of rest and vise versa
*change it’s motion (movement)
*change it’s shape or size
*rotate (turning effect)
What are the ways to reduce friction?
- use a smooth surface
*add lubricant (oil or grease)
*install ball bearings or rollers
*streamline object (reduces air friction)
Does smaller area = greater pressure or smaller pressure?
Greater pressure
( Greater area = smaller pressure)
The incident ray, reflected ray and normal lie on the what?
The incident ray, reflected ray and normal lie on the same plane.
The angle of incidence is what to the angle of reflection?
The angle of incidence is equal to the angle of reflection.
When do regular reflections occur?
They occur on smooth or even surfaces and allows us to see the reflected image
When does diffused reflections occur?
It occurs on rough of uneven surfaces and there are no images.
What are the characteristics of mirror image?
1.virtual (only can be captured in the mirror)
2.erect (upright/ not inverted)
3.same size as object
4.same distance behind the mirror as object is Infront of the mirror
5.laterally inverted
Do concave mirrors make things bigger or smaller?
They make things seem bigger
concaves make things seem bigger while having a smaller field of view.
do convex mirrors make things look bigger or smaller?
they make things look smaller.
objects appear smaller while increasing the field of view
what is refraction?
refraction is the bending of light at the boundary of different optical materials(i.e. optical mediums) due to the change of speed in light as it passes from one material into another.
why do optical mediums affect the speed light travels at?
optical medums have a physical property called optical density which affects the speed light travels at through the medium.
optical density = how packed the object is
what is refracted ray?
it is the ray of light that moves away from the surface after refraction
what is refraction?
hint: its the short definition
it is the bending of light
what is reflection?
hint: it is the short definition
it is the bouncing of light.
what happens to light when at optically least dense?
*light travels faster
*light bends the least
least dense is air followed by water,glass and diamond
what happens to light at optically densest optical medium?
*light travels the slowest
*light bends the most
optically densest is diamond followed by glass, water and air
what are the effects of refraction?
hint: there are 2
- there is a misperception of depth
- the “disjointed” “broken” or “bent” straw.
why is there a misperception of depth?
because while light appears to travel in a straight line to our eyes, the light that comes from the object bent
objects in water appear shallower than it really is
why will there be the “disjointed”, “broken” or “bent” straw?
due to the refraction of light as it travels through the water, glass and then in air , it causes the straw to appear broken or disjoint.
what colour does white colour contain?
red,orange,yellow,green,blue,indigo and violet together.
white light splits into the seven colours when it undergoes dispersion
why do things appear in different colours?
the colour of the things you see is the colour that the “thing” relflects back into your eyes while it absorbs the rest of the colours.
black absorbs all colours. ( aka black is the absence of colour)
what is cell?
it is a power source
a battery is more then one cell
what is current?
current is the amount of energy flowing through a particular point in a circuit per unit time.
what is voltage?
voltage is the amount of energy needed to move a unit charge from one point to another point
what is resistance?
resistance is the opposition to the flow of the electric charges in an electric circuit
what isa resistor?
it is an electric component that is used to resist the flow of electric current
there are fixed and variable resistors
what is power?
power is the amount of electrical energy converted to other forms of energy per unit time
what is mV
meele volt
what is kV?
kilovolt
would kill you, very powerful
what is kW?
kilowatt
what is MW?
megawatt
how much does 1 kW equal to?
convert to watts
1 kW=1000W
how much is mega?
convert to million
mega= 1 million
what is kWh?
kilowatt-hour
how to find current?
I= V/R
I is the symbol for current
what is power measured in?
watts (W)
what is energy consumed measured in?
joules (J)
what is time measured in?
seconds (s).
how to calculate energy consumed?
E=p×t
how can kWh be calculated?
E=p×t
E in kWh, p in kW, t in h
how to use an ammeter?
connected in series to the circuit with the negative terminal of the ammeter connected to the negative side of the cell
an ammeter measures the electrical current
how to use a voltmeter?
it is comnected in parallel across to the electrical component it is measuring. the negative terminal of the voltmeter is connected to the negative side of cell.
the voltmeter measures the voltage of an electrical component
what are fixed resistors?
they have fixed values of resistance.
e.g. carbon film, carbon conposition, tin oxide and wire wound resistors
what are variable resistors?
they can vary the resistance
e.g. a rheostate is included in a circuit to vary the current flowing
what are effects that current can produce?
there are 2 effects
- heating (i.e.wires will become hot)
- magnetic (i.e. wites will have some magnetic properties)
what are the main causes of the hazards of electricity?
there are 3
- damaged insulators
- overheating of cables
- damp conditions
what are damaged insulators?
it is when insulating materials become worn with time and use, the bending and twisting causing cracks or breaks which expose the conducting wires
exposed live wire causes severe electric shock (electrocution)
what is overheating of cables?
overheating(effect) of cables is when an unusually large current flows through the conducting wires done by overloading (cause) the power sockets using extensions (plug in alot of plug)
excess heat can cause overheating leading to a fire
what are damp conditions?
water is a conductor of electricity, providing a conducting path for a large current to flow. (R go down , I go up)
this increases the chances of getting an electric shock
what is a live wire?
it is conmected to the main supply and is responsible for drawing current from source
live wire is brown in colour
what is earth wire?
it is connected to metal case of appliance at one end and ground at the other. it diverts lwaked currents to the ground ( fail-safe)
earth wire is yellow and green striped in colour
what is neutral wire?
it completes the current and is responsible for returning current to the source. it is at 0V
neutral wire is blue in colour
what are the safety features?
there are 4
- circuit breakers
- fuses
- switch
- earthing ( earth wire)
what are circuit breakers?
they are safety devices that can trip and switch off the electrical supply when current drawn in circuits become too large
what are fuses?
a fuse ( connected to live wire) prevents too large a current from flowing through an appliance. it consists of a short thin piece of wire which becomes hot and melts when current flowing through is hreater then its rated value.(i.e. 3A,5A,13A , etc)
fuses should be slightly higher the current on appliance
too high of low and circuit will blow
what are switches?
switches are fitted into the live wire so that when an appliance is switched off is it disconnected from the high voltage supply.
if fitted wrong even when the switch is off the supply will run through
what is earthing?
earthing is the earth wire.
prevents users from getting ekectric shocks from leakage
what are the main components in nutrients?
there are 2
1.functions of water in humans
2.functions of water in plants
what are the functions of water in humans?
- maintain body temperature
- transportation of nutrients
- lubricating joints ( lubrication -eyes)
- soften stools (feces)
- main component of saliva
- removes toxins and waste products
what are the fucntions of water in plants?
- germination of seeds-growth of seeds
- keep plant firm
- cell turgidity
- photosynthesis -essential component for photosynthesis to take place
- transport minerals-transport nutrients
- cools down the plant
- medium to transport substances around the cell via xylem( water carrying tubes)
- acts as solvsnt for fertilizers and minerals
- pholem ( food carrying tubes)
photosynthesis - synthesis=making of something
what are the different nutrients?
there are 6
carbohydrates, fats, water, protein + minerals and vitamins
minerals - Ca, Na, Fe ( fortified)
vitamin - ( only need small amount)
vitamins - organic sources
minerals - doesnt come from organic sources ( can be made in labs)
What are carbohydrates?
elements:carbon, hydrogen, oxygen (CHO)
monosaccharides:GGF-glucose, galactose, fructose
disaccharides: SML-sucrose(glu+fru), maltose(glu+glu), lactose (glu+gal)
fromation of disaccharides: 2 monosaccharide molecules -(condensation reaction ) - 1 disaccharides + water
back to monosaccharides: 1 disaccharides + water - (hydrolysis/hydrotic reaction) - 2 monosaccharide molecules
polysaccharides:SCG- starch(straight chain), cellulose(straight chain), gycogen(branched chain- made and stored in animals, must be ‘chopped’ up (digestion) for use)
mono=1 di=2 poly= more then 2 saccrides= sugar
condensation reaction= chemicak reaction in which 2 molecules are joined togethere with the removal of 1 molecule ofwater
what are proteins?
elements:carbon,hydrogen,oxygen,nitrogen (CHON)
amino acids: building blocks of protein
polypeptides:formed when amino acids are linked up in straight chains
proteins: chains are coiled or folded giving protein a more complex and 3D shape(function) when these bonds are broken fhe protein loses its 3D shape, we say the protein ahs been denatured.
denaturation usually involves the loss of function of the protein
what are fats?
elements:carbon,hydrogen,oxygen(CHO)
fatty acids + glycerol(building blocks of lipids):1 fat molecule = 1 glycerol + 3 fatty acids (FA)
carbon and hydrgen are?
organic stuff
glycogen and starch are?
- insoluble in water - no change in water potential
- large molecules and cannot diffuse through all membrane-will not lost from all
- can be easily hydrolyzed to glucoss when needed for respiration
- compact shapes-use less space compared to smalller units
only glycogen,starch and cellulose are straight chains ( are all glucose)
what is the order in which the body uses the energy source?
there are 3
- carbohydrate
- fat
- protein
what is the test for starch?
iodine test
add a few drops of iodine to specimen
blue-black = starch present
brown= starch absent
what is the test for reducing sugars?
benedicts test
add 2cm³ of benedicts solution to 2 cm³ of glucose solution
shake the mixture
leave the test tube in a beaker of boiling water for 5 minutes
blue to green mixture(can see through) = traces of reducing sugars
blue to yellow/orange (unable to see through) = moderate amount of reducing sugar
blue to brick red (unable to see through) = large amounts of reducing sugar
what is the test for protein?
biuret test
add 1 cm³ of sodium hydroxide(alkaline) to 2 cm³ of egg whit solution
add 1% copper (ll) sulfate solution, drop by drop, shaking after every drop
shake well and allow the mixture to stand for 5 minutes
blue to violet= protein is present
remains blue = protein absent
what is the test for fats?
ethanol emulsion test
(liquid)
add 2 cm³ of ethanol to drop of oil in a test tube and shake the mixture thoroughly
add 2 cm³ of water to the mixture and shake mixture
(solid)
cut the solid food into small pieces in a test tube
add 2 cm³ of ethanol and shake mixture thoroughly
allow solid particles to settle
decant the ethanol into another tube containing 2 cm³ of water
a cloudy emulsion is formed=fats present
no cloudy whit emulsion= no fats present
what are some reducing sugars?
there are 5
monosaccharides -GGF ( glucose, galactose, fructose)
and maltose and lactose.
sucrose is not a reducing sugar
fats are?
fats are solid
(oils are liquid)
what is the definition of enzymes?
- they are proteins(proteinaceous)
- which work as biological catalysts
- that soeed up chemical reactions
- by lowering activation energy
- while remaining chemically unchanged at the end of the reaction
biological catalyst - are natural and speed up chemical reactions whole remaining chemically unchanged at the end
activation energy - minimum energy needed to kickstart a chemical reaction
what is an active site?
- part of the enzyme where the reaction takes place
- soecific shape for whatever its breaking down and it will ONLY break that down
enzymes has specific shape for target molecule. if molecule does not fit tightly (exact) with enzyme it will break away and free flloat until it find an enzyme that fits or until it slowly breaks down by self.
what is an enzyme-substrate complex?
a temporary structure formed when enzyme and substrate (molecule to be broken down) collide in the correct position
what is activation energy?
the minimum energy needed to kickstart a chemical reaction.
enzymes speed up reactions by lowering activation energy
what is enzyme specificity?
substrate is complementary in shape to the active site of the enzyme (same shape)
each type of substrate can only fit into each type of enzyme
what are the effects of temperature on enzyme?
lower then optimal: -enzymes move very slowly (low kinetic energy)
-lower rate of effective collisions
-fewer E-S complex per unit time
- fewer products per unit time
optimal temp: where there is highest rate of enzyme activity.
higher then optimal: enzymes denatured
what are the effects of pH on enzymes?
optimal pH: where there is highest rate of enzyme activity
higher/lower then optimal:enzymes denatured
optimal pH differs for every enzyme
what is denaturation?
- it can be cause by heat or chemicals like acids and alkalines
- enzyme has specific 3D shape
=Denaturation=loss of 3D shape=loss of active site, substrate cannot bind=no E-S complex=no product/loss of product. - dentaured enzymes get unfolded and become random shapes
enzymes…?
-speed up digestion
-are proteins by nsture
-can be ‘reused’ ( therefore only small amount is needed)
how does the naming of enzymes work?
they are generally named after their substrates name
e.g.-maltase(enzyme) digests maltose(substrate)
-sucrase(enzyme) digests sucrose(substrate)
(substrate-ase digests substrate)
there are exceptions to this rule. e.g. pepsin,rennin,trypsin(all protease)
amylase(found in mouth)-digests starch(not sweet)-maltose(sweet)
pepsin(found in stomache)-digests protein
lingase-digests lignin(lignin hardens the outside of xylem(water carrying tubes), making it more stable)
enzyme can digest enzyme if they are complementary in shape, occuring only when enzyme fails to function, i.e. gets denatured. when this happens a special enzyme eill digest the denatured enzyme into amino acids, which can be used to form new enzymes.
