Triple Paper 2

Question 1

Describe the changes involved in the way energy is stored

when systems change

Answer 1

Whenever a system changes there is a change in the way some or all of the energy is stored. A car driver braking in an emergency - kinetic energy is transferred into thermal energy of the surroundings by the work done by the force of friction on the brakes

Question 2

Why when energy is transferred in a closed system is there no net change to the total energy in that system?

Answer 2

Because energy can only be transferred and not created or destroyed and nothing can enter the system so the there is no net change

Question 3

What are the different ways that the energy of a system can be changed

Answer 3

mechanical work - a force moving an object through a distance
electrical work - charges moving due to a potential difference
heating - due to temperature difference caused electrically or by chemical reaction
radiation - energy tranferred as a wave, eg light and infrared - light radiation and infrared radiation are emitted from the sun

Question 4

What are the different ways that the energy of a system can be changed?

Answer 4

mechanical work - a force moving an object through a distance
electrical work - charges moving due to a potential difference
heating - due to temperature difference caused electrically or by chemical reaction
radiation - energy tranferred as a wave, eg light and infrared - light radiation and infrared radiation are emitted from the sun

Question 5

What is the equation for work done?

Answer 5

Work done =force x distance

Question 6

What is energy transferred equal to?

Answer 6

It is equal to work done

Question 7

What is the equation for gravitational potential energy?

Answer 7

change in gravitational potential energy= mass × gravitational field strength × change in vertical height

Question 8

What is the equation for kinetic energy?

Answer 8

kinetic energy=0.5× mass × speed^2

Question 9

How are system changes energy is

dissipated so that it is stored in less useful ways?

Answer 9

Whenever there is a change in a system, energy is transferred and some of that energy is dissipated . Dissipation is a term that is often used to describe ways in which energy is wasted. Any energy that is not transferred to useful energy stores is said to be wasted because it is transferred to the surroundings

Question 10

When do mechanical processes become wasteful?

Answer 10

They become wasteful when they
cause a rise in temperature so dissipating energy in heating
the surroundings

Question 11

What is power?

Answer 11

The rate at which energy is transferred

Question 12

What is the equation for power?

Answer 12

power= work done÷ time taken

Question 13

What is the equation for efficiency?

Answer 13

Efficiency=useful energy transferred / total energy transferred

Question 14

Describe situations where forces can cause rotation

Answer 14

Forces can cause an object to rotate and the turning effect of the force is called a moment. If a resultant force acts on an object about a fixed turning point (the pivot) it will cause the object to rotate

Question 15

What is the equation for momentum?

Answer 15

moment of a force = force × distance normal to the direction of the force

Question 16

What is the principle of momentum where rotational forces are in equilibrium?

Answer 16

the sum of clockwise moments = the sum of anti-clockwise

moments

Question 17

Describe the structure of the atom, limited to the position,

mass and charge of protons, neutrons, and electrons

Answer 17

Proton-In nucleus, a charge of 1+ and relative mass of 1

Electron-Outer shell, Charge of 1- and relative mass of 1/2000

Neutron-In nucleus, neutral charge and a relative mass of 1

Question 18

Draw an electric circuit diagram representing them with
the conventions of positive and negative terminals, and the
symbols that represent cells, including batteries, switches,
voltmeters, ammeters and a variable resistor

Answer 18

Draw and compare to the circuit by searching it up or give to Nat

Question 19

Draw the symbols for: cells, including batteries, switches, voltmeters, ammeters, resistors, variable resistors, lamps, motors, diodes, thermistors, LDRs, and LEDs

Answer 19

Search up the answers

Question 20

What is the difference between a series and a parallel circuit?

Answer 20

In a series circuit, all components are connected end-to-end, forming a single path for current flow. In a parallel circuit, all components are connected across each other, forming multiple sets of electrically common points.

Question 21

How is a voltmeter connected with a

component to measure the potential difference across it?

Answer 21

It is connected in parallel

Question 22

What is potential difference?

Answer 22

The voltage or the energy

transferred per unit charge passed

Question 23

What is the equation for energy transferred?

Answer 23

energy transferred = charge moved ×

potential difference

Question 24

How is an ammeter connected to a component to measure the current in the component?

Answer 24

It is connected in series

Question 25

How can an insulator be charged by friction, through the transfer of electrons?

Answer 25

When insulating materials rub against each other, they may become electrically charged. Electrons, which are negatively charged, maybe 'rubbed off' one material and onto the other. The material that gains electrons becomes negatively charged. The material that loses electrons is left with a positive charge.

Question 26

Why does a material gaining electron make it become negatively charged?

Answer 26

Because it gains the Negatively charged electrons making it become negatively charged

Question 27

Why does a material losing electrons make it become positively charged

Answer 27

Because if it loses something negative it will become positive

Question 28

Recall that: Like charges ____? Unlike charges_____?

Answer 28

Like charges-repel | Unlike charges-Attract

Question 29

Explain shocks from everyday objects in terms of the movement of electrons

Answer 29

The build-up of electrostatic charge can be quite dangerous and can cause sparking (also known as an electric shock) A static electric spark occurs when: Two objects are charged by friction They become oppositely charged The large surplus of electrons causes electrons to 'jump' across to an object that is neutral

Question 30

Explain how lightning happens in terms of the movement of electrons

Answer 30

In a storm, clouds move over each other This causes them to become charged when electrons are transferred between them Since the ground is neutral, the negative charges from the cloud jump to meet the positive charges on the ground creating a giant spark

Question 31

Explain how a ballon sticks to a wall

Answer 31

Rubbing a balloon on a woollen jumper transfers electrons onto the balloon by friction The balloon is now negatively charged whilst the jumper is left positively charged The wall is still neutral, however, when the balloon is placed near the wall, the positive charges in the wall are brought to the surface because they are attracted to the negative charge of the balloon Since opposite charges attract, the balloon sticks to the wall from only the electrostatic attraction

Question 32

How does earthing remove excess charge by movement of electrons?

Answer 32

Grounding is the process of removing the excess charge on an object by means of the transfer of electrons between it and another object of substantial size. When a charged object is grounded, the excess charge is balanced by the transfer of electrons between the charged object and a ground.

Question 33

How do insecticide sprayers use electrostatic charges?

Answer 33

The static drops spread evenly as they all have the same charge and repel each other. They are also attracted to the earth, so will fall quickly and are less likely to blow away.

Question 34

Describe some of the dangers of sparking in everyday situations, including fuelling cars, and explain the use of earthing to prevent dangerous build-up of charge

Answer 34

It is dangerous when there are flammable gases or a high concentration of oxygen. A spark could ignite the gases and cause an explosion. It is dangerous when you touch something with a large electric charge on it. The charge will flow through your body causing an electric shock. This could cause burns or even stop your heart. A person could die from an electric shock.

Question 35

What is an electric field

Answer 35

The region where an electric charge experiences a force

Question 36

Describe the shape and direction of an electric field around a point charge

Answer 36

There are uniform diagonal lines that go away from the point

Question 37

Describe the shape and direction of the electric field between parallel plates

Answer 37

The field between two parallel plates, one positive and the other negative, would be a uniform field. The field lines would be straight, parallel and point from positive to negative.

Question 38

Explain how the concept of an electric field helps to explain the phenomena of static electricity

Answer 38

Static electricity is the result of an imbalance between negative and positive charges in an object. These charges can build up on the surface of an object until they find a way to be released or discharged.These charges are in a electric field

Question 39

Recall that: Unlike magnetic poles _____? Like magnetic poles ______?

Answer 39

Unlike magnetic poles attract | Like magnetic poles repel

Question 40

What are the uses of permanent magnets?

Answer 40

There are many uses for a permanent magnet. The most common application of a magnet is for the purpose of attracting other magnetic items, but it also has functions in electronic equipment. Permanent magnets are used in computers, motors, cars, generators, headphones, speakers, sensors, etc.

Question 41

What are the uses of temporary magnets?

Answer 41

Temporary magnets are used in cranes to move magnetic objects from one place to another by lifting up magnets. Uses of temporary magnets would be paper clips and nails and other soft iron items as examples used for temporary magnets

Question 42

What is the difference between permanent and induced magnets?

Answer 42

A permanent magnet produces its own magnetic field. An induced magnet is a material that becomes a magnet when it is placed in a magnetic field

Question 43

Describe the shape and direction of the magnetic field around bar magnets

Answer 43

The lines of magnetic field from a bar magnet form closed lines. By convention, the field direction is taken to be outward from the North pole and in to the South pole of the magnet.

Question 44

Describe the use of plotting compasses to show the shape and direction of the field of a magnet and the Earth’s magnetic field

Answer 44

Magnetic fields can be mapped out using small plotting compasses : place the plotting compass near the magnet on a piece of paper. mark the direction the compass needle points. move the plotting compass to many different positions in the magnetic field, marking the needle direction each time. To find the Earth's magnetic field you can just use a compass and it will always point north

Question 45

How does the behaviour of a magnetic compass relate to the evidence that the core of the Earth must be magnetic?

Answer 45

Because the compass always points north we know that the Earth's core must be magnetic

Question 46

How can an alternating current in one circuit induce a current in another circuit in a transformer?

Answer 46

A primary potential difference drives an alternating current through the primary coil the primary coil current produces a magnetic field, which changes as the current changes the iron core increases the strength of the magnetic field the changing magnetic field induces a changing potential difference (voltage) in the secondary coil the induced potential difference produces an alternating current in the external circuit

Question 47

What can a transformer change?

Answer 47

The sizeof an alternating voltage

Question 48

How do you calculate the missing voltage or the missing number of turns?

Answer 48

Potdiff across primary = no of turns in primary | Potdiff across secondary no of turns in secondary

Question 49

Why, in the national grid, is the electrical energy transferred at high voltages and then transferred at lower voltages for domestic uses

Answer 49

When a current flows through a wire some energy is lost as heat. The higher the current, the more heat is lost. To reduce these losses, the National Grid transmits electricity at a low current. This needs a high voltage.(It is done with a step up transformer) Because the higher the voltage the less the current needs to be.However it needs to be used in homes so is decreased by a step down transformer

Question 50

Where and why are step-up transformers are used in the transmission of electricity in the national grid?

Answer 50

Step-up transformers are used at power stations to produce the very high voltages needed to transmit electricity through the National Grid power lines

Question 51

Where and why are step-down transformers are used in the transmission of electricity in the national grid?

Answer 51

Step-down transformers are used locally to reduce the voltage to safe levels.

Question 52

What is the power equation (for transformers with 100% efficiency)

Answer 52

Potential difference across primary coil × current in primary coil = potential difference across secondary coil × current in secondary coil

Question 53

What is the advantage of power transmission in high-voltage cables

Answer 53

The primary reason that power is transmitted at high voltages is to increase efficiency. As electricity is transmitted over long distances, there are inherent energy losses along the way. High voltage transmission minimizes the amount of power lost as electricity flows from one location to the next.

Question 54

What are the properties of solids?

Answer 54

They have a fixed shape and cannot flow The particles cannot move from place to place They cannot be compressed or squashed The particles are close together and have no space to move into They have a regular pattern and vibrate

Question 55

What are the properties of liquid?

Answer 55

They flow and take the shape of their container The particles are free to move around each other They cannot be compressed or squashed The particles are close together and have no space to move into They have a random arrangement and move around each other

Question 56

What are the properties of gases

Answer 56

They flow and completely fill their container The particles can move quickly in all directions They can be compressed or squashed The particles are far apart and have space to move into They have a random arrangement and move around quickly

Question 57

What is the equation for density

Answer 57

Density=mass/volume | P=m/v

Question 58

What are the differences in density between the states of matter?

Answer 58

There is only a small difference between the density of a liquid and its corresponding solid, eg water and ice. This is because the particles are tightly packed in both states. The same number of particles in a gas spread further apart than in the liquid or solid states. The same mass takes up a bigger volume. So the density goes solid > liquid > gas because it is mass divided by volume the bigger the volume the smaller the density

Question 59

True or False? When substances melt, freeze, evaporate, boil, condense or sublimate mass is not conserved and these physical changes don't differ from some chemical changes because the material does not recover its original properties if the change is reversed

Answer 59

When substances melt, freeze, evaporate, boil, condense or sublimate mass IS conserved and these physical changes DIFFER from some chemical changes because the material RECOVERS its original properties if the change is reversed

Question 60

Why does atmospheric pressure vary with height above the Earth's surface?

Answer 60

Atmospheric pressure decreases as the height of a surface above ground level increases. This is because, as the altitude increases: the number of air molecules decreases meaning the weight of the air decreases.

Question 61

What is the pressure in a fluid due to?

Answer 61

It is due to the fluid and the atmospheric pressure

Question 62

Where does the pressure in a fluid cause pressure?

Answer 62

Normal to any surface

Question 63

How is pressure related to force and area/what is the equation for pressure?

Answer 63

Pressure=force/area | P=F/A

Question 64

How does pressure in fluid increase with depth and density?

Answer 64

Pressure increases as the depth increase and pressure also increase with an increasing density

Question 65

Why does the pressure in a liquid vary with density and depth?

Answer 65

The pressure in a liquid is different at different depths. Pressure increases as the depth increase. The pressure in a liquid is due to the weight of the column of water above. Since the particles in a liquid are tightly packed, this pressure acts in all directions.The pressure in a liquid is different at different depths. Pressure increases as the depth increase.The pressure in a liquid is due to the weight of the column of water above. Since the particles in a liquid are tightly packed, this pressure acts in all directions

Question 66

What is the equation for pressure (due to a column of liquid)

Answer 66

pressure due to a column of liquid= height | of column× density of liquid× gravitational field strength

Question 67

Describe the construction of an electrical used to investigate the relationship between potential difference, current, and resistance for a resistor and a filament lamp.

Answer 67

Connect the circuit like the typical one. Adjust the variable resistor so that the potential difference is very low or zero at the start. Record the reading on the voltmeter and ammeter. Use the variable resistor to increase the potential difference. Record the new readings on the voltmeter and ammeter. Repeat steps three to four, each time increasing the potential difference slightly. Reverse the power supply connections and repeat steps two to six. Repeat the experiment but replace the fixed resistor with a bulb. Plot a graph of current against potential difference for each component. (Use the equation resistance=pd/current)

Question 68

Describe the core practical: Investigate the densities of solids and liquids

Answer 68

To find the densities of an object you need to use a eureka can this will for a solid allow you to find the volume and using scales you can find the mass and then use the equation p=m/v. For a liquid: 1) the measuring cylinder on the top pan balance and measure its mass. 2) Pour 50 cm3 of water into the measuring cylinder and measure its new mass. 3) Subtract the mass in step 1 from the mass in step 2. This is the mass of 50 cm3 of water. 4) Use the measurements to calculate the density of the water.

Question 69

Describe the Core Practical: Investigate the properties of water by determining the specific heat capacity of water and obtaining a temperature-time graph for melting ice

Answer 69

Place 50 grams of crushed ice straight from the freezer into the calorimeter. Place the immersion heater into the central hole at the top of the calorimeter. Clamp the thermometer with its bulb in the ice but near the top of the ice. Record the temperature of the ice. Connect the heater to the power supply and joulemeter, turn it on and record the temperature every 20 seconds. Continue until the thermometer bulb is no longer under the level of the water.