Category : 5th Class
This lesson will help you to:-
QUICK CONCEPT REVIEW
Work is done only when an object moves over distance on applying force.
Example: If you move a pencil, work is done, but after applying lots of force, if you are not able to move a pencil, no work is done.
Force is needed to pull or push something. You cannot move an object without using force. For example: you cannot push a ball without using force. To move a light object like pencil, you will have to use less force and to move a heavy object like a table; you have to apply more fore. Force can slow, stop or change the direction of a moving object.
Push: An act of exerting force on someone or something to move them away from oneself.
Pull: An act of taking hold of something and exerting force to draw it towards oneself.
There are various types of forces that are either exhibited by or on a body.
Misconnect: Friction force is considered as the negative work.
Concept: Work done can never be negative. Friction force slows down the sliding motion and thus is very crucial in day to day activities.
Misconnect: An object at rest has no energy.
Concept: The object at rest has potential energy. As the object starts moving, its potential energy converts into kinetic energy and then into other energies.
Types of Forces
Friction Force: Friction is resistance of solid surfaces, layers and material elements. Gravity: The force that attracts a body towards the centre of the earth or towards any other physical body having mass is called gravity.
Buoyant Force: Buoyancy is the upward force on an object produced by the surrounding liquid or gas in which it is fully or partially immersed, due to the pressure difference of the fluid between the top and bottom of the object.
This force enables the object to float or at least seem lighter.
Buoyancy is important for many vehicles such as boats, ships, balloons, and airships.
Magnetic Force: When two magnets come together or push away from each other, they exhibit magnetic force.
Applied Force: It is a force that is applied to an object by a person or another object.
Energy is the ability to do work. When you apply force on an object, your uses energy. Energy can be neither created nor destroyed.
Example: to move a table, you apply force and to do so your body uses energy. Your body produces energy from the food you eat. A moving car uses energy from the fuel it burns. Whenever force is applied, energy is used.
SOURCES OF ENERGY
We use energy from different sources in our day to day life.
TYPES OF ENERGY
Machines are used to make certain tasks easy. Machines like bicycle, sewing machine, etc., are made up of many ports. They are called complex machines. Some machines are very simple. Like any other machine, a simple machine helps us to perform certain tasks with ease.
Example: Needle, knife, etc.
Simple machines: Simple machines are able to increase a force when energy is added to them. This means that they make work easier. Simple machines can also change the direction of the force or make things move faster. Examples of classic simple machines are:
A complex machine is a machine that is made up of more than one simple machine. The simple machines work together to make work easier. Cars and bicycles are examples of complex machines.
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