Page 89 - Science class 4

Inclined PlanePlanePlane
Inclined
Inclined
An inclined plane is a sloping surface
which is used to push or pull heavy

objects to a certain height. A strong,
smooth board placed at an angle can

be used as an inclined plane.

You must have seen heavy cartons being loaded onto a truck by pushing the

carton up an inclined board.

Screws
Screws
Screws
A screw is actually an inclined plane wrapped around a
cylinder that has a sharp pointed end. Screws are turned
with the help of a screwdriver. As they rotate, they also
move forward. So, they help to attach things to each other.

Wedge
Wedge
Wedge
A wedge has at least one slanting surface ending in a
sharp edge. This helps to cut things. A good example
is an axe with which we can cut wood.

Knowledge Plus ENERGY AND ITS SOURCES

We are able to work only when we have
Energy that a moving object has
energy. Energy is the ability to do work.
is called kinetic energy.
We need energy to do everything right

from the basic things like walking, reading and talking, to the difficult tasks

like lifting, carrying and climbing. Energy exists in various forms, such as :
chemical, mechanical, heat, light, electrical, magnetic and sound energy.
Energy changes easily from one form to another.

Sources
Sources of Energyof Energy
Sources of Energy
1. The Sun
The main source of all energy on the Earth is the sun. The energy that we

get from the Sun is called solar energy .
Plants use solar energy to make food in the
green leaves. Food has energy stored in

the chemical form. We get heat and light
energy from the Sun. Solar energy can also

be used to generate electricity.