5th Class Science Work, Force, Energy and Simple Machines Work Force and Energy

WORK, FORCE AND ENERGY

FUNDAMENTAL

FORCE

A force is a push or pull. It can help us to do the work. It brings the change or tries to bring the change in the state of motion. Force may be of various types, e.g. mechanical, gravitation, magnetic, frictional, electric and buoyant force.

WORK

Whenever an applied force is capable to move an   object on which the force is applied, the work is done. No change in position means no work. Work is measured in joule, which means the object is displaced by one metre with one Newton Force.

SIMPLE MACHINE

            It is a tool that makes the work easy. For example

• Lever
• Pulley
• Wheel and axle
• Inclined plane
• Screw
• Wedge

LEVER

A lever is a simple machine. It is a rigid rod that turns around a fixed point called fulcrum. It consists of fulcrum (f), load (w) and effort.

Levers classified into three kinds according to the position of fulcrum, load and effort.

Type of Lever

PULLEY

• The pulley is a wheel with a grooved around its rim. The wheel turns around an axle. A belt or string fits into groove. There are two types of pulleys, a fixed pulley and a movable pulley. The pulley used for drawing water from a well is fixed pulley, movable pulleys along with fixed pulleys are used to lift woods.

WHEEL AND AXEL

• The wheel and axle consists of a wheel attached to a smaller axle so that these two parts rotate together in which a force is transferred from one to the other.

INCLINED PLANE

• An inclined plane, also known as a ramp, is a flat supporting surface tilted at an angle, with one end higher than the other, used as an aid for raising or lowering a load.

SCREW

• A short, slender, sharp-pointed metal pin with a raised helical thread running around it and a slotted head, used to join things together by being rotated so that it pierces wood or other material and is held tightly in place.

WEDGE

• A wedge consists of two inclined planes that meet at a sharp edge.

ENERGY

• Energy is the capacity to do the work. Energy is neither created not destroyed but only transformed in another form. Total energy is always fixed.
• Renewable source of energy, which are constantly replenished by nature, e.g. Sun, wind and water.
• Non-renewable source of energy: Takes millions of years to be formed. These sources of energy are called non- renewable source of energy, e.g. Fossil fuels (Petrol, diesel) they are limited in amount and will be exhausted one day.