Force, work and energy · बल, कार्य और ऊर्जा
A free Physics lesson for Class 4 children.
A push or a pull is called a force.
A force can move a thing, stop it, or change its shape or direction.
Work is done when a force moves something.
If you push a wall and it does not move, no work is done.
We need energy to do work. We get our energy from food.
Plants make food using the energy of the Sun. So the Sun is our main source of energy.
Energy has many forms, such as heat, light, sound and electricity.
Friction is a force that slows down moving things.