# GCSE Physics Unit 2 - Electricity, acceleration, forces and radioactivity

Notes covering;

• the three pin plug, fuses and earthing
• speed, velocity and acceleration
• braking and stopping distances
• forces and friction
• momentum
• the history of the atom
• nuclear fission vs nuclear fusion

Created for the AQA 2011 exam - any changes to the specification are not included.

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• Created by: Sarah
• Created on: 03-01-12 18:50

## Pages in this set

### Page 1

3Three Pin Plugs

This plug has
o Copper wires as copper is a good
electrical conductor
o Plastic covers as they are electrical
insulators and prevent electric shocks.
o Brass pins are electrical conductors
and do not rust.
o A fuse as a safety precaution.

However, appliances that are plastic…

### Page 2

Earthing

Earthing is a safety precaution. An earth wire is connected to the metal case of
the appliance, so that if the live wire becomes loose and touches the casing, the
current immediately flows to earth and blows the fuse, making the appliance safe to
touch.

For example

This washing…

### Page 3

Charge in Circuits

In wires
o Electrons carry the electric current.
o They are negatively charged.
o They pass along wires from the
negative to the positive terminal.
o This is the opposite direction to
current.

In liquids [electrolysis]
o Ions move towards electrodes.
o Positive ions move to the…

### Page 4

Oscilloscopes

No voltage connected.

DC No Time Base DC with Time Base
(Direct Current flows in one direction) (Source = Battery)

AC No Time Base AC with Time Base
(Alternating Current flows from positive
to negative to positive etc.)

Mains Voltage is AC, the live
wire equalling 240V and the…

### Page 5

Speed, Velocity & Acceleration

Distance ­ how far an object has moved (m)
Displacement ­ how far an object has moved in a certain direction (m)
Speed ­ the rate of change of distance with time (m/s)
Velocity ­ the rate of change of displacement with time (m/s)
Deceleration ­…

### Page 6

area under graph = speed x time = distance

Braking Distances

Stopping distance is comprised of two distances:

o Thinking Distance.
The distance travelled by the car as the driver reacts to a situation before he
brakes. Factors include drugs, alcohol, tiredness and speed of the car.

o Braking Distance…

### Page 7

Forces

A force is a push or a pull and is measured in Newtons (N). More than one
force can act on an object

These forces are balanced. They have no
effect on the object's movement. The object
either remains stationery or moves at the
same speed.

However, when forces…

### Page 8

Falling in a Fluid

If an object falls through a gas or a liquid, it encounters resistive forces acting in
the opposite direction, either air resistance or liquid resistance. As the speed of the
object increases, so will these resistive forces until a point where the forces are
balanced. This…

### Page 9

Newton's Laws of Motion

1. Acceleration of an object is proportional to the applied force.
2. Acceleration of an object is inversely proportional to its mass.

Energy Equations

If an object can recover its original shape then elastic potential energy is the
energy stored in an object when work has…

### Page 10

Momentum & Collisions

Momentum is conserved in any collision or explosion providing no external
forces are acting, thus total momentum before collision = total momentum after
collision. In general

BEFORE AFTER

(m¹ x u¹) + (m² x u²) = (m¹ x v¹) + (m² x v²)

Sometimes the trucks could…