While revolution is often used as a synonym for rotation, in many fields, particularly astronomy and related fields, revolution, often referred to as orbital revolution for clarity, is used when one body moves around another while rotation is used to mean the movement around an axis.

When an object moves in a straight line then the motion is considered as translational but when the same object moves along an axis in a circular path then it is known as Rotational Motion.

ω = ω 0 + α t ( constant α ) , ω = ω 0 + α t ( constant α ) , where ω 0 is the initial angular velocity. These equations can be used to solve rotational or linear kinematics problem in which a and α are constant.

ROTATION : The earth rotates about an imaginary line that passes through the North and South Poles of the planet. This line is called the axis of rotation. Earth rotates about this axis once each day (approximately 24 hours). The period for the Earth to revolve around the sun is 365.24 days or one year.

Rotations About The Origin

• 90 Degree Rotation. When rotating a point 90 degrees counterclockwise about the origin our point A(x,y) becomes A'(-y,x).
• 180 Degree Rotation. When rotating a point 180 degrees counterclockwise about the origin our point A(x,y) becomes A'(-x,-y).
• 270 Degree Rotation.

The rule for a rotation by 90° about the origin is (x,y)→(−y,x) .

Reflection – of a polygon A transformation where each point in a shape appears at an equal distance on the opposite side of a given line – the line of reflection. Every point on the original triangle is “reflected” in the mirror and appears on the right side an equal distance from the line.

Under a point reflection, figures do not change size or shape. While any point in the coordinate plane may be used as a point of reflection, the most commonly used point is the origin. When you reflect a point in the origin, both the x-coordinate and the y-coordinate are negated (their signs are changed).