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TOPIC: FORCE
Definition: Force is a push or pull. A force is that which changes or tends to change the state of rest or motion of a body.
Force= Mass (M) ×acceleration (A)
F = MA.

Types of Force: All forces (interactions) between objects can be placed into two broad categories: contact forces and Non- contact (action-at-a-distance force)
Contact Forces : this is a force applied directly on an object. Examples include frictional forces, Tension force, normal forces, and air resistance forces, spring force.
Non- Contact Force: this is a force exerted on a body from another body in a distance (action-at-a-distance forces) includes gravitation, electrostatic and magnetic
forces.

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Measuring Force:
Force is measured using either the English System of Measurements or the International System of Units (SI).SI: Newton (N) 1N = 0.225 lb;
One Newton (N) of force is defined as the amount of force needed to accelerate 1 kilogram (kg) of mass at a rate of 1 meter per second squared (m/s2).

Some types of Forces explained
Friction – Friction is a force caused when one object rubs against another. It works in the opposite direction of the main force.
Gravity – Gravity is a force caused by a large body, such as the Earth. Gravity pulls objects toward the Earth with an acceleration of “g” which equals 9.8 m/s2.

Electromagnetic force- is a force associated with electric and magnetic fields.
Nuclear force – are the forces that hold atoms and their particles together.

Tension – A pulling force that is exerted by a string, cable, or chain on another object. Elastic – An elastic force is a force exerted by an object trying to return to its natural length.
FRICTION
All types of surfaces like solids, liquid and air offer the force of friction.

Definition: friction is the force that opposes or resists movement when two surfaces are in
contact.

Factors affecting friction
Irregularities on two surfaces in contact.

Friction will increase with increase in faith.

Two kinds of friction
Static friction: this is the force of friction that must be overcome to move an object at rest.

Kinetic friction: this is the force of friction that opposes a moving object.

Friction: A Necessary Evil:
Friction is a necessary evil because it has both harmful and beneficial effects.

Friction makes movements possible
Friction help to tighten or hold surfaces together e.g bolts and nuts, ladder on the wall, screws etc.

It results in wear and tear of shoes and tyres, machine parts, clothes etc. it causes monetary loss
Friction make us spend money on lubrication
Heat is generated by friction, which results in wastage of energy.

Ways to reduce friction
Lubricating oil and grease are used in machines to reduce friction between moving parts.

Ball bearings coverts sliding friction into rolling friction
The use of air cushion or graphite power.

Ways to increase friction
Soles of shoes are made rough to increase friction
Treads of tyres are deliberately made so that a good road grip can be achieved with the help of friction.

The use of sand papers or surface roughening materials on surfaces. 