Additional Revision

Question 0

What are the six steps to following standard Procedure

Answer 0

1) Read the procedure and make sure you understand everything
2) complete a risk assessment
3) collect the equipment and materials you need and set out your work
4) select instrument that have appropriate sensitivity and use them to make accurate observations or measurements
5) follow the instructions knew step at a time
6) identify possible sources of error and repeat observations and measurements where necessary to improve reliability

Question 1

Explain what is mean by Standard Procedure how and why it is carried out

Answer 1

Once a scientist has a hypothesis he will carry out an experiment to prove it, using standees procedures.
Standard Procedures are agreed methods of work, chosen because they’re safety, effectiveness and accuracy.
Slandered Procedure is so so that everyone carry a out the experiment the same way, helping add consistency to the results.
Slandered procedures can be agreed wishing a company, nationally or internationally.

Question 2

How and why do scientists draw conclusions

Answer 2

They sued the evidence collected in their experiment to draw a conclusion
They present their evidence and their conclusions in a report so that other scientist can read about it

Question 3

What are hazard symbols used for and why

Also what are the 10 most common ones used

Answer 3

Hazard symbols are used to show if something is dangerous and why
The 10 most common are: flammable- catch fire easily eg petrol
Irritant- can cause reddening or blistering of the skin eg sodium hydroxide
Toxic- can cause death either by being swallowed, breathed in or absorbed through the skin eg cyanide
Harmful- like toxic but a little less dangerous eg copper
Explosive- can explode eg peroxide
Radioactive- gives off radiation eg plutonium
Oxidising- these provide oxygen which allows materials to burn more fiercely eg liquid oxygen
Biohazard- contains biological materials that can be harmful eg bacteria
Dangerous for the environment- can damage the environment eg ammonia
Electrical Hazard- could give you an electrical shock eg power supplies

Question 4

What are the two types of health and safety signs used in the workplace

Answer 4

Mandatory signs that give instructions that we must follow to keep us safe such as:
Eye protection must be worn 
Breathing masks must be worn 
Hand protection must be worn 
Eat protection must be worn 

Safe condition signs mark the location or thing you might need in an emergency such as: 
First aid 
Emergency eye wash 
Emergency shower 
Fire alarm point

Question 5

What are the four types of fire extinguishers and what are their specific uses

Answer 5

Red- water, used for wood, paper, coal
Black- carbon dioxide, used for wood, paper, coal,liquids, electrical equipment
Cream-foam, used for wood, paper, coal, liquids
Blue- dry powder, used for wood, paper, coal, liquids, glasses, electrical equipment

Question 6

What are the laws put into place to make sure that people are Safe at work

Answer 6

The health and safety act at work of 1974 is a legislation that deals with occupational Heath and Safety

The health and safety executive is on organisation set us by the government to help protect people health at their work and at their school
They also check the rules given in the health and safety act at work are being followed

Question 7

What are the reps taken when you do a risk assessment

Answer 7

Their are 5 stages:

1) look for hazards
2) assess who may be harmed and how
3) decide what action if any needs to be taken to reduce the risk
4) document the findings
5) review the assessment regularly

Question 8

Why is it important it check health and safety and you do up your experiment and how can this be done in school

Answer 8

This is important so that the hazard risks stay low.
In school this includes:
Bags being stored away safely
Long hair is tied back
The appropriate safety equipment is being used eg goggles, heat proof mat
Apparatus is away from the edge of the bench

Question 9

What are the different careers involved in Healthcare and what to they entail

Answer 9

Pharmacist
Know about drugs and now they can be used
Help patients get as much benefit as possible from the medication they are taking
Advising doctors on which medication is most effective for a patient
Dietician
Use their knowledge of food to prevent medical conditions a associated with food
Help people with special dietary requirements to analyse what they can and can’t eat
Help people with eating disorders
Nutritionist
Give people information about food nutrition
Help people understand how to eat a balanced diet and stay healthy
Sport nutritionists work with athletes and suggests diets to enable them to do better in sport
Physiotherapists
Experts in joints and muscles
Help treat medical conditions that prevent people from moving easily eg age eg arthritis
Help treat and rehabilitate people after serious injuries eg learning how to walk again

Question 10

What is the role of fitness partitioner

Answer 10

Help to keep people fit such as
Fitness trainers, supervise exercise program’s in gyms and leisure centres and provide personal training
Coaches, provide technical training for particular sporting events and general fitness training
Sports psychologists, help athletes improve there physical fitness and strengths

Question 11

What are the 4 main components of hair blood and what are their uses

Answer 11

The blood is a fluid made up of cells, platelets and plasma:

Red blood cells, transports oc yen from the lungs to all feels in the nosy
White blood cells, help fight infection
Platelets, help the blood to clot at the the site in the wound
Plasma, this is he liquid that carries everything about eg glucose

Question 12

Blood is carried around the body by blood vessels, state there names and uses

Answer 12

Arteries- carry the blood away from the heart
Capillaries- involved in exchanging of material at the tissue
Veins- carry the blood to the heat

Question 13

What is the function of the arteries

Answer 13

Carry blood under pressure
The heat puma the bold at high pressure, so the artery walls are strong and elastic
The walks are thick compared to the size if the lumen, contain thick layers of muscles to make them strong
The high pressure means that if you press down lightly on an artery you can feel a pulse each time the heart beats

Question 14

What is the function of the blood capillary

Answer 14

Arteries are bunched capillaries
They are too small to see
Carry the blood close to every cell in the body to exchange substances with them
Have permeable walls, can move in and out
They supply nutrients and oxygen and take away waste CO2
Walls are only one cell thick, this increase the rate of sigh angle by decreasing the distance over which it happens

Question 15

What is the function I’d the gains that take blood back to the heat

Answer 15

Capillaries join to make veins
The blood is at a lowered pressure so the walls don’t need to be as thick as the artery wall
Have bigger lumens than the arteries to help the blood flow although they have lower blood pressure
Have valves that help the blood flow in the right direction

Question 16

What is the fiction if the heart

Answer 16

Pumps blood around the body
Seep rated into two parts, left and right
The right, pumps blood to the lungs
The left pumps blood to the rest of the body
The heart, books and the blood vessels together are called the cardiovascular system

Question 17

What is the Thorax and it’s uses

Answer 17

The top part of the body

Lugs, like big sponges
Trachea, the pipe connecting your mouth to the nose and lungs, splits into two tubes called bronchi goes to each lung
Bronchi, splits into progressively smaller tubes called bronchioles that end with small bags called alveoli, this is where oxygen moves into the blood and carbon dioxide moves out
Ribs, protect the lungs and heat ect, important in breathing
Intercostal muscles, muscles between the ribs
Diaphragm, large muscle at the bottom of the thorax which is all important for breathing

Question 18

Why at the intercostal muscles and diaphragm important in helping us to breath

Answer 18

During ventilation their is a pressure that causes air to enter our lungs:
Breathing In,
The intercostal muscles pull the rib cage up and out, the diaphragm contracts and flattens out, the contracting muscles make the cheats cavity larger, this decreases the pressure inside the lungs so air is drawn in

Breathing out
The intercostal muscles relax, the rib age frogs in and down, the diaphragm relaxed and arches up, the relaxed muscles makes the chest cavity smaller, causing an increase in the pressure inside the lungs and air is forced out

Question 19

What are the two thing measured by a spirometer

Answer 19

The tidal volume,
The amount you breath in or out with raven breath
To measure this you would breath normally for 3 minutes
Add your reading and device by 3 to get the average

Vital capacity
The most amount of air you can possibly breath in or out in one breath
To measure up would put the spirometer to your mouth, breath in as far as you can and out and far as you can
Repeat two home, use the highest value

Question 20

What is breathing rate

Answer 20

The number of breaths per minute
Can be measure by counting the number of breaths they take in a minute
Not reliable because you don’t take the same number if breaths per minute
It is more reliable yo take an average

Question 21

How does exercise affect breathing rate and total volume

Answer 21

When you exercise your breathing rate increase in two ways:
Your breathing rate increases, you take kite breaths per minute
Your total volume increases, you take deepens breaths

Question 22

What is respiration

Answer 22

It is the process of braking down the glucose to release energy
When you exercise al lot of the energy released in reparation is use to make your muscles contact
The heat and lungs allow glucose and oxygen to be transport to the muscles for respiration
Their are two types of respiration aerobic and anaerobic

Question 23

What is aerobic respiration

Answer 23

Uses prenatal of oxygen
Happens when their is plant of oxygen
It is the most effective ya to release energy from glucose
It’s turn glucose from food and oxygen from your lungs into Corbin dioxide and water
Glucose +oxygen> carbon dioxide+water (+energy)

Question 24

What is anaerobic respiration and what dies it entail

Answer 24

Happens when there enough energy available The brake down of glucose in incomplete and and lactic acid I'd produced Glucose> lactic acid (+engery) This is not the best Waac to convert glucose into energy as it releases much less energy than aerobic respiration

Question 25

Explain the oxygen given by anaerobic respiration

Answer 25

When you respire anaerobically lactic acid builds up in the muscles which is painful After restoring the anaerobic respiration, when you stop exercising you'll have an oxygen debt where your muscles are still sort of oxygen as they have not been getting enough for a while You'll need extra oxygen to convert the lactic acid back into glucose Meaning you have to keep breathing head and your heart rate will stay high a while after exercising to repay the dept

Question 26

How do you measure heart rate

Answer 26

To measure heart rate you measure plus rate Place two finger on wrist or neck and count the number of pulses you feel for minute Each plus is one heartbeat

Question 27

How does exercising increase heart rate

Answer 27

Muscles need energy for respiration and contract, when you exercise you muscles contact more frequently so you need more energy, this energy comes from increased respiration This increase in respiration mean you need more oxygen into the cell When you excise two things happen you your heart rate, your hear rate increases, the volume of blood pumped in each heartbeat increases This means that oxygen and glucose can be delivered more quickly Breathing rate and tidal volume also increases and get more oxygen in the blood and CO2 out When you do really vigorous exercise your body can't supply oxygen to your muscles quickly enough so they start resourcing anaerobically

Question 28

How can you measure recovery time hen

Answer 28

Measure your heart rate at rest Run for about 20 minutes Measure your pula rate very 2 minutes till back to normal The time it takes from when you stop exercising for your oils to renunciation to normal is recovery time

Question 29

What are the types of thermometer that can be used to measure nosy temperature

Answer 29

A clinical thermometer, a bog started thermometer that you stick under you armpit or tongue A electronic digital thermometer, a fancy thermometer that you put in your year, it gives a digital reading A liquid crystal thermometer, a plastic strip that's placed on the skin and changes colour to show the temperature

Question 30

How does the thermoregulatory centre in the brain act to controls your body temperature

Answer 30

When you are too hot You swat,when it evaporates it transfers heat to the environment cooling you down The blood vessels that supply the skin capillaries dilate, allowing more blood to flow near the surface of the skin, so you lose more heat to the surroundings When you are too cold You body make very little swat Blood vessels that supply skin capillaries contact, meaning less heat is lost from the blood to the surroundings, as less blood can flow to the surface of the skin

Question 31

How and why do we need to balance our water content

Answer 31

Water is lost from the body by Urine, swat, faeces The kidneys controls the amount of water in our body's by the amount of urine we use When we are hydrated the kidneys produce more urine and it will be pail and dilute When your dehydrated the kidneys produce less urine and it will be darker and concentrated

Question 32

How does insulin and glucose controls blood sugar levels

Answer 32

Carbohydrate foods out a lot of glucose into the blood by the gut Normal respiration in blood removes glucose from the blood Vigorous activity also removed glucose from the blood In circulating good glucose levels get too high, the pancreas release a hormone- insulin Insulin stimulated the liver to take up glucose from the blood and store it as an insoluble carbonate call glucose

Question 33

What are the measures for testing glucose

Answer 33

Testing the urine Dip a glucose test strip into the urine sample Compare against colour chart given There should be any glucose in the urine, a positive could be diabetics Testing the blood Prick your finger using a sterile pin Put a drop of blood onto the glucose test strip Compare to the manufactures colour chart The strip turns out a different colour depending in the amount of glucose in the sample This helps a diabetic to work out how much insulin to inject You could also get a diabetic blood glucose reader that gives you a accurate reading

Question 34

Explain how muscle strath is measured

Answer 34

The grip test: Adjust the dynamometer to match your hand size Hold the hand grip dynamometer in your right hand, in line wit your forearm, with your elbow at a right angle to your body Grip the dynamometer as hard as you can, repeat 3 times Record the best reading

Question 35

Explain how muscles pull on bones to move them

Answer 35

The job of a skeleton is yo support the boys and allow it to move as well as protect vital organs A point where to or mire bones meet is called a joint Joint allow Lima to move in different directions The bones at a joint are held together by ligaments which stabilise the joint Bones are attached to the muscle by tendons Muscles move bones at a joint by contracting Tendons can't stretch much so at a joint it pulls on the bone

Question 36

How and why do muscles usually come in antagonistic pares

Answer 36

Muscles can inky pull on the bone, they can't move This is why they usually come in pairs On one muscle in a pain contact the other detracts,vice versa The biceps and triceps are antagonist muscles: When the biceps contract the triceps relaxes, and the lower arm moves upwards, when the triceps contracts the biceps relaxes moving the lower arm downward Together they work at a level where the elbow is the pivot

Question 37

What are synovial joints

Answer 37

Most of the joints in the body are synovial joints The end of the bone in a synovial joint is covered in cartilage The joint is surrounded by a synovial membrane The synovial joint, produces synovial fluid to lubricate the joints allowing them to move mire freely

Question 38

What is turning force

Answer 38

When a force acts on something which has a pivot, it's create a Turing or twisting force A Turing or twisting force is called a moment Moment= force x perpendicular distance

Question 39

What are the types of injures

Answer 39

skeletal-muscular injuries, where your bones, muscles, cartilage, tendons, ligaments or joints are damages Some of the skeletal injuries are Ligament damage, when it has been stretched or pulled Pulled or toenail muscles, torn because of sudden starching Ruptured tendons, tendon brakes usually because of over stretching Dislocation- bone is pulled out of its normal position or twisted Fractured bones, bone brakes because it's put under a lot of stress Torn cartilage, cartilage or joint tears she to sudden impact or violent twisting These injuries are treated by a sports physiotherapy, usually using massage and manipulation techniques They might also putt other and exercise program to help hey you fit again

Question 40

Explain how the arm works at a level so it has movement

Answer 40

Works at a level with the elbow as a pivot Meaning when a gourde acts on the art here is a moment For the arm to keep still the moment has to be the same as the moment weight If the muscle has a bigger moment than the weight the arm will lift If the weight has a bigger moment than the muscle the arm will move down Because the distance between the muscle and the pivot is much smaller than the distance between the weight and the pivot the muscle has to apply a much bigger four car to generate the same moment

Question 41

What are the disadvantages of replacing joints

Answer 41

The surrounding tissues may become inflamed and painful, causing by the body's reaction to the material that the joint is made from Hip dislocation is more common with artificial joints as are blood clots There is am infection risk as with any surgery The length of the legs may be slightly different, causing difficulty walking Artificial joints don't last forever, usually being replaced writhing 12-15 years

Question 42

What are the requirement when making artificial joints

Answer 42

Durable material, last longer The material shouldn't react with anything in the body or activate the body's immune system, otherwise could make the person I'll Lightweight, aid mobility Other requirement depend on the joint replacement for example: If the joint replacement helps the body carry weight (hip) it need to be strong and sturdy- titanium If the joint being replace requires a lot of movement (knee) it needs to be flexible and strong- plastic Many modern joint are made from ceramics as it is smother than metal and plastic and helps reduce the amount of friction in the joints

Question 43

Why do larger body mass need more energy

Answer 43

Every cell in the body needs energy, the bigger you are the mire cells you have, he more energy you need. You also need energy to move your body as it takes more energy to move bigger mass.

Question 44

How does the dietary requirement of an tallest differ from a normal person

Answer 44

Need plant of carbohydrate to provide energy for training and competing Might need extra protein to build and repair muscles They might need to dip rink more water to stay hydrated and regulate their body temperature They might need to monitor their fat intake to ensure it stays at a healthy level

Question 45

What techniques would a sports nutritionist and a sport dietician use to study an talents current waging habits in order for them to give advice

Answer 45

24 hour dietary recall The athlete is asked to recall everything they have eaten or drank in the last 24 hours- this is a quick and east method of seeing there eating habits diet diaries The athlete is asked to write down everything they have eaten or drank in a week or longer, the nutritionist examines the diary and works out the athletes nutritional intake and provides advice

Question 46

Explain why an athlete would sobering increase there carbohydrate intake

Answer 46

Carbohydrates are broken down in the body and release glucose Excess glucose can be stored in the muscles as glycogen When the muscles need more energy they take the glycogen, convert it back junto glucose which is broken down into energy Carbohydrate loading, increases the amount of glucose stored on the muscles, meaning the athlete can run for longer without getting tired

Question 47

Explain why some athletes need a high protein diet

Answer 47

Protein is needed by the body to build and repair muscles Body builders need it to increase muscle mass They might also drink protein shakes Eggs Oats Milk Meat

Question 48

During easer size your nosy repairs more, what does this mean

Answer 48

You use up a lot of glucose by braking it down to release energy You get warmer, you sweat to cool down Swat contains lots of water and ions called electrolytes, hour loosing them After excise you need to relinquish your body's supplies

Question 49

What is the use of isotonic drinks

Answer 49

Designed yo help athletes recover after exercise | They contain water, glucose, electrolytes and some concentrates

Question 50

Why are isotonic drinks better to drink than water when you are dehydrated

Answer 50

Drinking water can make you bloated and suppress your thirst, this can put you of drinking enough to replace your loss If you don't have enough ions you struggle to regain the water you drink, it takes longer to be absorbed Because isotonic drinks replace the ions lost siring exercise, your nosy can train the danger in the drink Isotonic drinks replace the electrolytes as well as the water

Question 51

What are hypertonic and hypotonic drinks

Answer 51

These contain water and electrolytes but different amount if glucose Hypertonic drinks contain more glucose than isotonic drinks, they can be used to supplement the body's daily carbohydrate intake and give loads of energy Hypotonic drinks contain less glucose than isotonic drinks, they can be used to quickly replace fluid that have been lost to sweating but don't contain loads loads if calories

Question 52

Why do products need to be safe and do their job properly

Answer 52

People would be upset if they broke or didn't do a quality job A bad product might be dangerous All new products are tested to make sure they are safe for purpose, this means that

Question 53

What are the organisations that help to promote good standards

Answer 53

The British Standards Institute- BS Each standard is a document describing how well a product should do its jobs, how safe it should be ect If a product has their logo it means it has been tested and is safe for commercial use The European Committee for standardisation -CE A verity of products have to meet a certain legal and safety standards before they can be sold in the European Community , including products made in Europe and those imported in

Question 54

What is mean by compression and tensile strength

Answer 54

The object is being crushed of squished, it is under compression The object is being stretched, tension Materials that have compression strength can resist being crushed or squished Materials that have high tensile strath can resist being stretched

Question 55

Describe material usefully, using the right terminology

Answer 55

Stiffness/ Flexibility If a material does not deform much or at all when you apply atop of erasure to if- stuff If a material changes shape easily- flexible Some materials can be made ridged by using a different stiffer material to change its shape (make it thicker) Toughness/ Brittleness A tough material can deform quite easily without braking A brittle material brakes before if deformed very much Hardness A hard material resists to stretching or indentation A harder material will be able to cut through a softer one Density A dense material has a large mass contained in as all volume

Question 56

How would you compare the stiffness of different materials

Answer 56

God the material being tested under a clamp Gradually increase the load on the material by adding weights, Measure the existent ion of the material each tome using a ruler You can compare the stiffness by 1) Plotting a graph with the force on the x-axis and extension on the y-axis, the stiffness of the. Arterial is shown by the shallowest gradient 2) Calculations Hooks law Force (N)= Constant (N/cm) x Extension (cm) Or Constant (N/cm) =Force (N)/ Extension (cm)

Question 57

Hope can you measure the strength of a material

Answer 57

Tensile Strength, you use a clap with a ruler on the end, add weight onto it until it brakes The load at which it brakes is its tensile strength Compressive Strength, you can use a clap with a ruler on the end, tighten the clamp until the object brakes The load which the object brakes is it's compressive strath Stress: Stress is hen amount of pressure that is being out on a big of a material, you can find the stress on a piece of material using: Stress (N/cm2) =Force (N) /Cross-sectional area (cm2) The greater the stress needed to brake a material, the stronger the material is

Question 58

How can you work out Density

Answer 58

Density is a measurement of how heavy a material is for its size Equation: Density (g/cm3) =mass (g)/volume (cm3) You can find the mass of a piece of material by weighing it using a balance You can can find the volume of a piece of material by using by putting in the water and measuring how much the water level rises

Question 59

How can you compare the hardness of materials by denting them

Answer 59

Drop the weight down a tube The weight will hug a nail and push it into the material it's testing Measure the depth of the dent The hardest material will have the smallest dent

Question 60

How can impact be tested by toughness

Answer 60

Put a deep groove in the material you are testing Brake the materials one at a time by swinging a pendulum hammer from a set night, measure how night the hammer swings after it brakes each material Tough material absorb mire energy when they brake than brittle materials Meaning the pendulum will have less energy after braking the material and won't swing as high The toughest material will be the one where the pendulum swings the least distance after braking the material

Question 61

Testing materials for corrosion

Answer 61

Corrosion is when a material reacts with the things in its environment Nd gradually brakes down When a material corrodes it's properties change To test weathers a material will corrode or not we leave it it air or water for a fixed time If after that time, the materials properties haven't changed much, it's said to be resistant to corrosion

Question 62

Electrical conductivity

Answer 62

The ability to conduct electricity High electrical conductivity- conducts electricity really well, a large electrical current can flow through them for a given voltage Eg gold, silver, copper Materials with low electrical conductivity don't conduct electricity very well Materials with an electrical conductivity at nearly zero and called electrical insulators Eg glass, plastic

Question 63

Comparing electrical conductivity

Answer 63

You can com pair the electrical conductivity of materials by putting a piece of each material, one at a time, into a circuit along with a ammeter The ammeter measure the current flowing through the circuit The material with the highest electrical conductivity will be the one which allows the nuggets current to flow when it is put in the circuit

Question 64

Thermal conductivity

Answer 64

The ability to conduct high energy Some materials conduct heat better than others The ability to conduct heat energy us called thermal conductivity Materials that have a very low thermal conductivity (air) are called thermal insulators- great energy flows through then very slowly

Question 65

Comparing thermal conductivity

Answer 65

Put one elf of the material above a Bunsen burner flame Measure the temperature of the other end using a digital thermometer, time how long it takes for this end to reach a particular temperature The material with the highest thermal conductivity will be the one which takes the least amount of time for the other end to reach that temperature Make sure all the materials at the start are the same temperature- fair test

Question 66

Ceramics

Answer 66

``` Are very hard but brake very easily Brake when bent, not flexible Poor conductors of heat, low thermal conductivity High melting points Resistant to chemical attacks ```

Question 67

Uses of ceramics

Answer 67

Space shuttles Used at heat resistant tiles against the earths atmosphere- ceramics because: They have low thermal conductivity, stops the shuttle from getting dangerously hot They have high melting points, if the tiles started to melt they would not be very useful in protecting the shuttle Catalytic converters Useful in modern cars to remove some of the harmful gases that come out the exhaust The temperature catalytic converters work at is around 350-400('c) Catalytic converters contain a honeycomb structure donated in a thin layer of natal catalyst The honeycomb structure us made from ceramics, this is because ceramics have high melting points so they won't be damaged by the temperatures Artificial joints Ceramics are used to make artificial joints because: They are resistant to chemical attracts, meaning they won't react with anything in the body's hey are hard and durable, they won't need replacing too often Ceramics are smooth, this reduces the amount of friction in the joints

Question 68

The properties of metals are due to their bonding

Answer 68

The atoms are held together by metallic bonds These bonds allow the outer electrons of each atom to move freely This creates a 'sea' of free electrons that can move through the metal This is a very sting attraction between the positive metal ions and the negative free electrons

Question 69

Metals are strong but flexible

Answer 69

Not all metals have the same properties, nut in general They has high tensile strength, this is because the metallic bonds holding the atoms together are strong and difficult to brake They have high thermal conductivity, this is because the free electrons can move and carry heat energy through the metal They flexible and malleable, this is because the atoms in the metal are arranged in layers which can slid over one another

Question 70

Alloys are harder than pure metals

Answer 70

An alloy is a mixture of two or more elements, at least one is metal Different elements have differentiate atoms, when another element is added to the pure metal it will upset the layers of metal atoms, making it mire difficult for them to slide over one another This means that the alloys tend to be harder than pure metals

Question 71

The properties of polymers are dire to there structure

Answer 71

Polymers are made up of atoms which are joined together to form long chains Lots of these changes can then be pack together side by side The atoms in the chains are held together by sting covalent bonds The chains are held together by weaker forces of attraction

Question 72

Polymers have some same characteristic properties

Answer 72

Because they have the same structure most polymers share certain properties: They are flexible, this is because the bonds between the chains are weak, so the chains can easily slide across one another as the polymer bends They have low thermal conductivity, this is because the chains tend to be packed together loosely, so heat energy is transferred slowly through the polymer They have low density, this is because the chains in many polymers have branches coming off them, so they can't pack tether very tightly

Question 73

Thermoplastic and thermosetting polymers

Answer 73

The strath of the force between the chains affect the polymers properties: Thermoplastic polymers- have very weak forces of attraction between the chains, which are easy to overcome, as a result the polymer is flexible and easy to melt into a new shape, you can melt these polymers and remould them as many times as you like Thermosetting polymers Have strong cross- like chains (covalent bonds) between the chains, these hold the chains tighter in a solid structure. As a result the polymer doesn't soften when it's heated and it can't be remoulded The strength of the four e of attraction between the chains of a polymer is also affected by: The length of the chain, long chains are held together mire strongly than shorter chains The amount if branching in the polymer, chains with fewer branches can pack toothed more closely, this increase the strath of the force of attraction between them In general, polymers with strongest forces of attraction between the changes are stinger, denser and hand higher melting pints than polymers with weaker forced between the chains

Question 74

Polymers can be used to make sporting equipment

Answer 74

Polyester Is a type of polymer, it's lightweight, durable and water resistant,- football shirts, sports vests, fleecy jumpers and outdoor jackets Lycra- Elastane Another type of polymer, it's has excellent elasticity, it's lightweight, durable, resistant to water and sweat. Sportswear needs to be stretchy to be comfortable so is often made with Elastane- swim ware, wetsuits, cycling shots, athletic and aerobic clothing Polystyrene Crash helmets need to be strong, lightweight and flexible. The hard putter casing is made from strong polymers and the inner lining is usually made from polystyrene foam, which is flexible and crushes on impact

Question 75

Kevlar

Answer 75

It is a polymer that is used to make: Tennis rackets Some tennis rackets have string made from Kevlar because they hate light, flexible and very strong. They can absorb along of energy when the racket huts a ball without braking Golf Clubs Kevlar is added to the shaft of some gold clubs because it is light and when the golf club is used to hit the bold ball, it can absorb large amounts if energy without braking. It gives the golf club strath without making it too heavy to swing

Question 76

Composites

Answer 76

Are made up of two or more different materials. The properties of a composite depend on the properties of the materials it is made from, example: Wood-plastic composite are made from wood and plastic, they behave like wood and can be shaped using woodworking tools- but water resistant plastic Cement is made from ceramic and metal, it's durable and heat resistant but malleable Carbon Fibre, it is a mixture of plastic and fibres made of carbon, it has low density( plastic) but is very strong (carbon) Fibreglass is made from a plastic and a fibres made of glass, if has low density (plastic) but is very strong (glass)

Question 77

Uses of composite metals

Answer 77

Laminated windscreens are made from 2 layers of glass and one of plastic, it makes it safer because the plastic will hold the glass shards together Sports materials are made using carbon fibre Bike frames, CRP is much lighter than traditional materials like aluminium and steel Racquet frames, CRO is strong enough to hold the strings in tension and lightweight enough for easy handing Yachts, CRP is sting and lightweight so it's used to make very speedy yachts Racing car brakes are made using Ceramics and carbon because when a car brakes, there friction between the brake lads and the black discs, this friction makes the discs and lads very hot, break discs need to have a high melting point, if job it would start melting and be useless in stopping the car. The disc must also be durable so they don't wear down too quickly, the high melting point and harness of ceramics makes them ideal for discs and pads, mixing the ceramics with the carbon makes them lighter which helps the car go faster

Question 78

Materials can be natural or synthetic

Answer 78

Natural materials are found naturally in the environment (wood, wool, silk, metals) Synthetic materials are not found naturally, we have to make them ourselves (plastic, polyester) Advantages Synthetic materials are often cheaper than natural materials Synthetic materials can be mire durable than natural materials You can change the properties of a synthetic material to match what you need the material for You can make a synthetic material in whatever shape or size you need Disadvantage Many synthetic materials come from unsustainable sources (crude oil) Many synthetic materials are no biodegradable and are difficult to dispose of

Question 79

You can choose materials depending on their properties

Answer 79

Materials with a low thermal conductivity are used to keep things hot or cold Low density materials are used to make objects that need to be light Flexible materials are used to make things that need to end and stretch Shock-absorbing materials are used it make things that need to withstand a big force Smooth materials are used to reduce friction Materials with a high tensile strength are used to provide support or carry loads