OBJECT IN MOTION

Rest. An object is said to be at rest if it does not change its postion with time, with respect to its sorroundings.

Example of rest body. A book lying on a table, a person sitting in a chair are the example of rest.

Motion. An object is said to be in motion if it changes its position with time, with respect to its sorroundings.

Example of motion body. A bird is flying in air, a man walking on road.

Rest and motion are relative. It means an object in one situation can be at rest but in another situation the same object can be in motion. e.g, a person sitting in a moving train is at rest w.r.t. his fellow passengers but is in motion w.r.t. the objects outside the train. another example is a person sitting in his house is at w.r.t. earth but is in motion w.r.t. other planets.

Types of motion of a body

1)Rectilinear or translatory motion

2)circular or rotatory motion

3)Oscillatory or vibratory motion

1)Rectilinear or translatory motion

Rectilinear motion is that motion in which a particle or point mass body is moving along a straight line.

Translatory motionis that motion in which a body, which is not a point mass body is moving such that all its constiuent particles moves simultaneously along parallel straight lines and shift through equal distance in a given interval of timee.g, A body slipping along the inclined olane has translotary motion.

Rectilinear or translatory motion can be uniform or non-uniform.

2) Circular or Rotatory motion

Circular motion is that motion in which a particle or a point mass body is moving on a circle.

Rotatory motion is that motion in which a body, which is not a point mass body, is moving such that all its constituent particles moves simultaneously along concenric circle, whose centres lie on a line, called axis of rotation and shift through equal angle in a given time.

circular or rotatory motion can be 2D or 3D motion and can be uniform or non-uniform. if the circular or rotatory motion is uniform , it is periodic also.

3)Oscillatory or vibratory motion

Oscillatory motion is that motion in which a body moveto and froor backand forth repeatedlyabout a fixed pointin a definite interval of time. In such a motion the body is confined within well defined limits on either side of means position. It means a periodic and bounced motion of a body about a fixed point is called an oscillatory motion.e.g., the motion of the pendulum of all clock is oscillatory motion.

If in the oscillatory motion, the amplitude is very small i.e,microscopic, the motion of a body is said to be a vibratory motion.