The+Physical+World+-+Big+Picture

__**The Big Picture**__

Everyday forces are “pushes” and “pulls” or combinations of them. These pushes and pulls create movement, changes of speed or direction and can also stop movement. We cannot actually see a force, but we can experience its effects or results. The greater the force, the greater effect it has. Forces act in opposition to one another. If one force is greater than another, an object will move in that direction. Forces include gravity, friction, magnetic and electrical forces. They can be measured in “Newtons” (N) using a force meter.  Newton devised three laws of motion which form the basis of theories of movement (mechanics):  A body will remain in a state of rest or constant motion in a straight line, unless it is acted upon by a force.  Force acting upon a body causes it to accelerate in the direction of the force; the size of the acceleration depends upon the size of the force and the mass of the body.  Whenever a force acts on an object, an equal and opposite force acts on the agent producing that force.      1 joule is the amount of work done when a force measuring 1 Newton is moved through a distance of 1 metre.  <span style="font-family: 'Arial','sans-serif';">The rate of doing work or transferring energy over a given time is **power.** This is measured in Watts. Machines are developed to make work easier. Machines need energy to make them work. They transfer energy from one form to another. Levers, gears and cogs assist energy transfer. <span style="font-family: 'Arial','sans-serif';">
 * <span style="font-family: 'Arial','sans-serif';">Newton’s First Law **
 * <span style="font-family: 'Arial','sans-serif';">Newton’s Second Law **
 * <span style="font-family: 'Arial','sans-serif';">Newton’s Third Law **
 * <span style="font-family: 'Arial','sans-serif';">Gravity **<span style="font-family: 'Arial','sans-serif';">results from an attraction between masses, which causes them to pull towards one another. The effect of this, because of the relative sizes of the Earth and objects on it, is that the objects are pulled towards the centre of the Earth. They are stopped by the Earth’s surface. In space, the force of gravity is less. This is experienced as “weightlessness”. Weight results from the force of gravity acting on a mass (the volume and material of which an object is made).
 * <span style="font-family: 'Arial','sans-serif';">Friction **<span style="font-family: 'Arial','sans-serif';">is the force that slows down moving objects. When friction is high, surfaces cannot move easily over one another. Friction acts in the direction opposite to that in which the object is moving. **Drag** is a type of frictional force. When an object pushes through a liquid or a gas, that liquid or gas pushes back on the object. This is the drag. Streamlining reduces drag.
 * <span style="font-family: 'Arial','sans-serif';">Magnetism **<span style="font-family: 'Arial','sans-serif';">results from the attraction that metals have on one another. Iron, nickel and cobalt are naturally magnetic. Magnets can make materials they attract magnetic. Magnets have two ends or poles. One of these ends will be attracted to the North Pole of the Earth, the opposite end of the magnet is attracted to the South Pole. Electricity can be used to create temporary magnets.
 * <span style="font-family: 'Arial','sans-serif';">Energy **<span style="font-family: 'Arial','sans-serif';">is the ability to do work or to make things happen. Energy can be found in many forms; electricity, heat, light, sound, chemicals, electricity, movement (kinetic), magnetism, or can be stored as potential energy. It can be transferred from one form to another. Energy is measured in Joules.
 * <span style="font-family: 'Arial','sans-serif';">Renewable sources **<span style="font-family: 'Arial','sans-serif';">of energy include moving water, wind, wave and solar power. These are sustainable forms of energy because they are continuously present due to the Earth’s natural systems. These are environmentally friendly sources of energy as they do not pollute the environment with waste products. Nuclear power produces dangerous waste products which are detrimental to the environment and to living things. It is not environmentally friendly.


 * Non-renewable sources** of energy include oil, coal and gas. These sources of energy were created millions of years ago from plant and animal remains. The geological processes which formed these materials have ceased. These resources will eventually run out. Energy is obtained from these materials by burning them. This produces waste gases which cause atmospheric pollution and climate change. These forms of energy are not environmentally friendly.

<span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">Conductors are materials that let electricity pass through them. They are usually metals. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">Insulators, like wood and wool, do not let electricity pass. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">A current flows around a circuit from one terminal of a battery to the other. Current cannot flow if there is a break in the circuit. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">One battery is correctly called a cell. When cells are connected together they then become known as a battery. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">Electric current is measured in Amps. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">Electric charge is lost as electricity flows around a circuit and eventually cells will become flat. The force or push that the cell gives the electrons to move around the circuit is called the electromotive force. This is measured in Volts. The current has to be driven or pushed through wires and bulbs. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">The part of the electromotive force which pushes the current across a particular part of a circuit, such as a buzzer, is called the potential difference across that buzzer. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">We measure the potential difference between two points on a circuit in volts and it is often referred to as the voltage. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">An electric current has a magnetic field. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;">· <span style="font-family: 'Arial','sans-serif';">If wire is coiled around an iron nail, passing a current through the wire will create a temporary magnet, or electromagnet. <span style="font-family: 'Arial','sans-serif';"> <span style="font-family: 'Arial','sans-serif';">
 * Electricity** is caused by a charged particle (electron) moving through a conductor (often a wire).
 * <span style="font-family: 'Arial','sans-serif';">Light and sound **<span style="font-family: 'Arial','sans-serif';"> are forms of energy that travel as waves or vibrations. Light waves travel in straight lines, but these can be reflected.