## 1.01 use the following units: kilogram (kg), metre (m), metre/second (m/s), metre/second^2(m/s^2), newton (N), second (s) and newton/kilogram(N/kg)

Make sure you are familiar with units for

Mass: kilogram (kg)

Distance: metre (m)

Speed: metre per second (m/s)

Acceleration: metre per second squared (m/s^2)

Force: newton (N)

Time: second (s)

Gravity: newton/kilogram (N/kg)

## 1.02 use the following units: Newton metre (Nm), kilogram metre/second (kgm/s)

the units of:

moment: Newton metre (Nm)

momentum: kilogram metre/second (kgm/s)

## 1.03 plot and explain distance-time graphs

A distance time graph has distance on the y axis (usually in metres) and time on the x axis (usually in seconds). The gradient of the line (change in y/ change in x) is the speed. If the line is flat then the object is stationary.

## 1.04 know and use the relationship between average speed, distance moved and time taken

To calculate average speed use

speed (m/s) = distance travelled (m)/ time taken (s)

## 1.05 practical: investigate the motion of everyday objects such as a toy car or tennis ball

Apparatus: stop watch and metre rule

mark the start and end positions for the know distance

use a metre rule to measure the distance

line up front of car with start point, release and start timer

move eyes to end point

stop timer when front of car passes end point

improve by repeating and averaging

make sure car starts from stationary

calculate average speed using : average speed = distance travelled/ time taken

## 1.07 plot and explain velocity-time graphs

on a velocity time graph the velocity-time graph the velocity is on the y axis (usually in m/s) and time is on the x axis (usually in s). If the line is flat then the object is moving at a constant velocity. the gradient of the line is the acceleration. The area under the line is the distance travelled.

## 1.08 determine acceleration from the gradiend of a velocity-time graph

Gradient = acceleration= change in y/ change in x = change in velocity/time

## 1.09 determine the distance travelled from the area between a velocity-time graph and the time axis

The area under the graph can be calculated as rectangles and triangles, or by counting boxes, is equal to the distance travelled.

## 1.10 use the relationship between final speed, initial speed, aceleration and distance moved

v2=u2+2as

v= final speed

u= initial speed

a= acceleration

s= distance moved

see all the rearrangements of this equation.

## 1.11 describe the effects of forces between bodies such as changes in speed, shape or direction

Forces can act on a body to change the velocity, so the speed, direction or both.

Or forces can change the shape of a body, stretching it squishing it or twisting it.

## 1.12 identify different types of force such as gravitational or electrostatic

different types of forces include:

Gravitational, weight, friction, electrostatic, air resistance (drag), tension (force in a spring), up thrust, lift, thrust

## 1.13 understand how vector quantities differ from scalar quantities

scalars are quantities with only magnitude (size)

vectors are quantities with magnitude (size) and direction

## 1.14 understand that force is a vector quantity

Force has a magnitude measured in (N) but it also has a direction, a push or a pull, up, down, left or right. So force is a vector.

## 1.15 calculate the resultant force of forces that act along a line

Forces along a line can combine by addition.

## 1.16 know that friction is a force that opposes motion

Friction is caused by surfaces rubbing. The force always acts in the opposite direction to motion.

## 1.17 know and use the relationship between unbalanced force, mass and acceleration : F = M x A

Force = Mass x Acceleration.

the force refers to the resultant force or the combined forces as seen in 1.15

## 1.18 know and use the relationship between weight, mass and gravitational field strength: W=mxg

Weight (N)= Mass (kg) x gravitational field strength (N/kg)

gravitational field strength on earth is approx. 10 N/kg and in GCSEs is taken to be 10 N/kg.

## 1.19 know that the stopping distance of a vehicle is made up of the sum of the thinking distance and the breaking distance

Stopping distance = Thinking distance + Breaking distance

## 1.20 describe the factors affecting vehicle stopping distance, including speed, mass, road condition and reaction time

Thinking distance Affected by:

Tiredness

Alcohol

speed of the car

Drugs (avoid as drugs can increase or decrease thinking distance)

Braking distance affected by:

Tyre conditions

Brake conditions

speed of the car

mass of the car

## 1.21 describe the forces acting on falling objects (explain why falling objects reach a terminal velocity)

Initially the only force is weight as drag is proportional to velocity. So the object accelerates downwards. As it accelerates the velocity so the drag increases as well. meaning there is a smaller resultant force downwards so a smaller acceleration. Until the object reaches a speed where the drag is equal to the weight meaning there is no acceleration, this velocity is know as terminal velocity.

## 1.22 practical investigate how extension varies with applied force for helical springs, metal wires and rubber bands

1. Set up your apparatus as shown in the
2. Measure the length of your spring without
any hanging masses.
3. Hang a mass of 100g on the spring
4. Measure the new length of the spring
5. Calculate the extension of the spring
6. Repeat steps 3-5 for increasing the mass
in increments of 100g
7. Take note of your results in the table.

## 1.23 know the the initial linear region of a force-extension graph is associated with Hooke’s law

Hooke’s law is that extension is directly proportional to force applied. This is shown by the straight line on the force-extension graph. Hooke’s law is obeyed as long as the line is straight.

## 1.24 describe elastic behaviour as the ability of a material to recover its original shape after the forces causing the deformation have been removed

Elastic behaviour is the ability of a material to recover original shape after the force is removed. in a spring this occurs when the force is lower than the elastic limit. loading and unloading force extension curves can be different as long as it returns to its original shape.

## 1.25 know and use the relationship between momentum, mass and velocity: P=m x v

momentum (kgm/s)= mass (kg) x velocity (m/s)

## 1.26 use the idea of momentum to explain safety features

To reduce the force experienced by the passenger you need to extend the time for a passenger to stop in a collision. As force is the change in momentum divided by time.

## 1.28 use the relationship between force, change in momentum and time take

Force is the rate of change of momentum. So Force (N) = change in momentum (kgm/s) / time (s)

## 1.29 demonstrate an understanding of Newton’s third law

Every action has an equal and opposite reaction.

Book pushes down on table, table pushes up on book. So book doesn’t accelerate.

Table pushes down on floor, floor pushes up on table. So table doesn’t accelerate.

## 1.30 know and use the relationship between the moment of a force and its perpendicular distance from the pivot

moment = force x perpendicular distance from the pivot

## 1.32 use the principle of moments for a simple system of parallel forces acting in one plane

The principle of moments states that when the clockwise moments are equal to the anticlockwise moments a body will be in equilibrium.

## 1.33 understand how the upward forces on a light beam, supported at its ends, vary with the position of a heavy object placed on the beam

when moments are taken from the right hand side as the block is a greater distance the force from the left hand pivot must be bigger to counteract it. The opposite is true for the left hand side.

## 2.01 use the following units: ampere (A), coulomb (C), joule (J), ohm (Ω), second (s), volt (V) and watt (W)

unit for:

current : Ampere (A)

charge : coulomb (C)

resistance : ohm (Ω)

time : second (s)

potential difference : volt (V)

power : watt (W)

2019-06-27T12:54:02+00:00Categories: 2 Electricity, 2(a) Units, Edexcel iGCSE Physics, Uncategorized||

## 2.02 understand how the use of insulation, double insulation, earthing, fuses and circuit breakers protects the device or user in a range of domestic appliances

Fuses Stop the flow of current by melting if the current is too high. So protecting sensitive components and people because if the components function at too higher temperature it can cause a fire.

Circuit breakers again break the circuit if current is too high.

Insulation and double insulation prevent people from touching exposed wires and getting shocks.

Earthing provides a low resistance path to the earth so if some one does come into contact with a current instead of flowing through them to the earth giving them a shock it flows through the earthing wire.

## 2.03 understand why a current in a resistor results in the electral transfer of energy and an increase in temperature, and how this can be used in a variety of domestic contexts

 Resistance causes transfer of electrical energy to heat energy. Some components are designed to have a high resistance to make sure this happens, for example electrical heaters that have lots of resistors to ensure a high resistance so a lot of heat is produced.

## 2.04 know and use the relationship between power, current and voltage: and apply the relationship to the selection of appropriate fuses

power (w) = current (A) x voltage (V)

when looking at a circuit a component will be given a power and a voltage appropriate to run at then the current can be calculated so the rating of the fuse can be selected for slightly higher than that.

## 2.05 use the relationship between energy transferred, current, voltage and time: E= I × V × T

Energy (J) = potential difference (V) x current (A) x Time (s)

## 2.06 know the difference between mains electricity being alternating current (a.c.) and direct current (d.c.) being supplied by a cell or battery

AC is constantly changing magnitude and direction. AC is how mains electricity is produced from turbines.

DC is constant. And is produced from a battery and used in some sensitive components like in computing.

## 2.07 explain why a series or parallel circuit is more appropriate for particular applications, including domestic lighting

• Components (e.g. bulbs) may be switched on/off independently.
• If one component breaks, current can still flow through the other parts of the circuit.
• Bulbs maintain a similar brightness.

• Fewer wires, cheaper and easier to assemble.
• Uses less power

## 2.08 understand how the current in a series circuit depends on the applied voltage and the number and nature of other components

Notes on current:

• As voltage increases the current also increases.
• In general, the more components in a circuit, the lower the current.

## 2.09 describe how current varies with voltage in wires, resistors, metal filament lamps and diodes, and how to investigate this experimentally

in the bellow diagram the red box could represent a wire, a bulb, a resistor or a diode.

By changing the resistance of the variable resistor the graphs are reproduced.

## 2.10 describe the qualitative effect of changing resistance on the current in a circuit

Since V = IR, as you increase the resistance in a circuit, the current will decrease.

## 2.11 describe the qualitative variation of resistance of light-dependent resistors (LDRs) with illumination and thermistors with temperature

LDR

As illumination increases, resistance decreases

Thermistor

As temperature increases, resistance decreases.

## 2.12 know that lamps and LEDs can be used to indicate the presence of a current in a circuit

A lamp can be added to a circuit to check for a current. If current is flowing, the lamp will light up.

## 2.13 know and use the relationship between voltage, current and resistance: V = I × R

Potential difference (V) = Current (A) x Resistance (Ω)

## 2.14 know that current is the rate of flow of charge

current is rate of flow of charge so I=Q/t

## 2.15 know and use the relationship between charge, current and time: Q = I × t

Charge (C) = Current (A) x Time (s)

## 2.16 know that electric current in solid metallic conductors is a flow of negatively charged electrons

Electrons are negatively charged and free to flow in a metal so carry charge

## 2.17 understand why current is conserved at a junction in a circuit

At a junction current ‘splits’ to take both paths.

It comes back together when the paths meet again.

I1 = I2 + I3 +I4

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Section 1: Principles of chemistry

a) States of matter

b) Atoms

c) Atomic structure

d) Relative formula masses and molar volumes of gases

e) Chemical formulae and chemical equations

f) Ionic compounds

g) Covalent substances

h) Metallic crystals

i) Electrolysis

Section 2: Chemistry of the elements

a) The Periodic Table

b) Group 1 elements: lithium, sodium and potassium

c) Group 7 elements: chlorine, bromine and iodine

d) Oxygen and oxides

e) Hydrogen and water

f) Reactivity series

g) Tests for ions and gases

Section 3: Organic chemistry

a) Introduction

b) Alkanes

c) Alkenes

d) Ethanol

Section 4: Physical chemistry

a) Acids, alkalis and salts

b) Energetics

c) Rates of reaction

d) Equilibria

Section 5: Chemistry in industry

a) Extraction and uses of metals

b) Crude oil

c) Synthetic polymers

d) The industrial manufacture of chemicals