Page 294 - General Knowledge

GENERAL KNOWLEDGE 2019

GENERAL SCIENCE : PHYSICS

1. NEWTON‘S LAW OF MOTION

Newton‘s First Law of motion
 If the net force acting on an object is zero, the object will remain at rest or move in a straight
line with a constant speed.
 An object at rest will stay at rest, an object in motion will stay in motion unless it is acted
upon by an unbalanced force.
 The motion of an object doesn‘t change until an unbalanced force acts on it.

 Net force means total force.
 The net force on an object determines how the motion of an object changes.
Balanced Force
 Two or more forces whose effects cancel each other out and do not change the motion of an
object.
 The net force is zero.
Unbalanced Force
 Two or more forces acting on an object that do not cancel, and cause the object to
accelerate.
 The net force is zero.
Friction
 A force that acts to oppose sliding between two surfaces that are touching.
 Types of Friction
 Static Friction – Surfaces stick together where they are in contact; due to the attraction
between the atoms on the two surfaces; no movement of an object.
 Sliding Friction – When a moving object slows down as it slides across an object; due
to the roughness of a surface.
 Rolling Friction – When an object rolls across a surface.
Inertia
 Inertia is an important property of matter.
 Inertia = property of matter that resists changes in its motion.
 Basically, because of inertia, objects want to maintain whatever motion they have.
 This was described by Galileo, later Sir Isaac Newton formulated it into one of his basic laws
of motion.
 Inertia is proportional to mass. The more mass something has, the more inertia it has a Mass
= measurement of Inertia
 The unit for mass is the kilogram (kg).
 Mass is also defined as the amount of matter something has.
 Mass is different than weight, which is the gravitational force of attraction between the earth
and an object.

The First Law
 An object remains at rest, and an object remains in motion with constant velocity unless it is
acted upon by an outside force.
 This law deals with inertia.

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