Work by the force
All of us do work. Even animals and machines do work. When we push or pull object, we feel exertion on arms and muscles. After some time, we get tired, it is because in doing work, we lose energy. Energy is thus, the capacity of doing work.
Direction of motion
When we apply force on a body at rest it comes into a state of motion. When we apply a force on a moving body in the direction of its motion, the moving body is moves faster. When we apply his force in the direction opposite to its motion, it moves slower and comes to rest.
Energy is required to do work
To do a work, energy is required. This energy is provided by a fuel. In steam engine, coal is burnt to produce steam which pushes the piston and makes the wheels of the engine roll. The engine pulls the heavy trains. Here the force of energy in the engine of the train is the coal acting as fuel. Similarly when human beings and other animals take food, it is broken up into pieces and provides the necessary energy to do different types of work. Here, food is the fuel for human beings and animals.
Forms of energy
Energy is of different forms, some of the important forms of energy are:-
1) heat energy
2) chemical energy
3) mechanical energy
4) electrical energy
5) Solar energy and etc.
*Heat energy is used in steam engines to pull the heavy trains. It is also used for cooking food, for warming rooms in winter, for melting metals and numerous in a thermal plant to produce electricity. Here chemical energy is first converted into heat energy and then heat energy is converted into electrical energy.
*Energy derived from moving water, steam or when force applied by hand, are the forms of mechanical energy. Water turbines and wind turbines provide mechanical energy which is converted into electrical energy.
*Electrical energy is used to light our houses. It is also used to drive mechanics, fans trains, motors and etc. grinding machines are run by electrical energy.
*Sun is the prime source of energy for all activities on earth. Energy derived from the sun is solar energy. We use it in from of solar.