Energy_Concept_1
Measuring energy
Measuring energy
To be capable of doing things — working, running, jumping or even standing sti\l you need energy. By doing those things, you can be said to be 4 using up' energy We take in energy mainly in the form of food (that is, chemicals from plants and/or animals), and we change it into movement, sound and heat
For any physical movement or change, energy is needed This energy is used up by the change or, if already there, released by it. -In mechanical terms the energy used (in joules) is defined as work done that the product of the force (in newtons) used to move a given mass and the distance (in metres) it is moved (see Chapter 4, page 64). For example, lifting a 10kg mass against the pull of Earth's gravity will require 98 newtons of force if the mass is lifted by 5rn, this will require an energy expenditure of 490 joules (the unit of energy). If the same mass is dropped, the same amount of energy is released as it fails.
The more massive an object is, the harder you push it or the further you move it, the mare energy you wilt use. Lifting half of a mass twice as far will use the same amount of energy,The more physical work we do. the more energy we use up hence the need for food to replace lost energy.
The concept of energy is often misunderstood and misused within science. it requires careful definition and explanation to distinguish the common usage of the word 'energy' (meaning 'being active') from the scientific concept of energy. Children need to be aware that the concept of energy applies to many different phenomena in a wide range of contexts.
Energy — the capacity to do work
In the average adult human, I kg of body fat contains enough stored energy for about 3.5 days' worth of normal activity.
If Britain were to increase the efficiency of its energy use by it would reduce its demand for electric power by 4 gigawatts per year that's the output of four nuclear power stations as big as the Sizewell plant. A gigawatt is 1000,000,000 watts (joules per second).
Energy only belongs to living things.
Well energy does belong to living things. Much of biological science describes and explains how energy flows within and between living things. But understanding energy requires children to go beyond such common usages as 'I'm tired I haven't got any energy 'left'. They need to appreciate that many other things' need energy: cars need energy from burning petrol; washing machines need the energy of electricity, and so on.
What are calories?
They are another unit of energy just as you can measure length in feet or in metres, you can measure energy in joules or calories, One calorie is equal to approximately 4.2 joules. Calories are most often used to the energy value of food in terms of its heat output when burned. The Calorie (note the capital 'C' is the unit used in the nutritional information on food packaging, and it is also called the 'kilocalorie' as it is equal to 1000 calories.
You should expect and plan to teach general ideas about energy through other areas of science (for example, when teaching about food and nutrition or heating and cooling), It should be a recurring theme when elements of the 'Energy concept chain' .