Embedded Files
objectives
objectives
Work
Work
- In everyday language, work might be writing an essay or digging the garden. But to scientists and engineers, work has a precise meaning; work is done whenever a force makes something move. The greater the force and the greater the distance moved, the more work is done.
- The SI unit of work is the joule (J):
- Work is calculated using this equation;
- work done = force X distance moved in the direction of the force
- In symbols;
- W = F X d
For example, if a 4 N force moves an object 3 m, the work done is 12 J.
Energy
Energy
- Things have energy - if they can be used to do work.
- A compressed spring has energy; so does a tankful of petrol. Like work, energy is measured in joules (J).
- Although people talk about energy being stored or given out, energy isn’t a Thing'.
- If, say, a compressed spring stores 100 joules of energy , this is just a measurement of how much work can be done by the spring.
- A fully flexed bow stores about 300 joules of energy.
4.1---Work--Energy--and-Power.mp4A Video showing Work, Power and Energy examples
- Energy can take different forms. These are described on the opposite page. To understand them, you need to know the following;
- Moving objects have energy. For example, a moving ball can do work by knocking something over.
- Materials are made up of atoms (or groups of atoms). These are constantly in motion.
- For example, in a solid such as iron, the atoms are vibrating. If the solid is heated and its temperature rises, the atoms move faster. So a material has more energy when hot than when cold.
- Atoms vibrating in a solid. The atoms have energy because of their motion.
Forms of Energy
Forms of Energy
To describe different forms of energy, these names are sometimes used:
Kinetic Energy
Kinetic Energy
Kinetic energy* This is energy due to motion. All moving objects have kinetic energy.
Potential Energy
Potential Energy
This is energy which an object has because of its changed position, shape, or state. There are several different types of potential energy. Here are some of the terms used to describe them:
Gravitational Potential Energy
Gravitational Potential Energy
A stone held up in the air can do work when dropped because gravity will pull it downwards. The stone has gravitational potential energy.
Electrical Potential Energy
Electrical Potential Energy
In circuits, the current is a flow of tiny charged particles called electrons.
These come from atoms. Electrons can transfer energy from, for example, a battery to a light bulb.
They have electrical potential energy, or electrical energy' for short.
Elastic Potential Energy
Elastic Potential Energy
- Elastic potential energy (strain energy)
- A stretched rubber band can do work when released, so can a compressed spring.
- Both have elastic potential energy.
Chemical Potential Energy
Chemical Potential Energy
Chemical potential energy
- When a fuel burns, its energy is released by chemical reactions.
- The energy stored in the fuel is called chemical potential energy, or chemical energy' for short.
- Batteries also store it. So do foods. Without it, your muscles could not move.
Nuclear potential energy
- An atom has a nucleus at its centre.
- This is made up of particles, held there by strong forces.
- In some atoms, the particles become rearranged, or the nucleus splits, and energy is released.
- This is called nuclear potential energy, or nuclear energy for short.
4.1---Nuclear-Reactor.mp4A video showing how Nuclear energy is 'made'
Energy that moves from one place to another
Energy that moves from one place to another
The following terms are sometimes used when describing energy which is being transferred from one place to another, or from one object to another:
Thermal Energy
Thermal Energy
- When hot objects cool down, their atoms and molecules slow down and lose energy.
- This is known as thermal energy, or heat. Engines use thermal energy to do work.
- For example, in a car engine, burning fuel produces hot gases which expand, push on pistons, and make them move. The motion is used to turn the wheels of the car.
Radiated Energy
Radiated Energy
- The Sun radiates light.
- Loudspeakers radiate sound.
- Light and sound both travel in the form of waves.
- These carry energy.
work and energy worksheet
work and energy worksheet
Please complete the worksheet and hand in on google classroom.
4.01---Work---Energy.docxPage updated
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