When an object changes its position with time, the object is said in the motion. And when an object does not change its position with time, the object is said in the rest.
To understand motion three things are necessary. These things are A reference point, time and object. This is because we observe an object in motion with the lapse of time and with respect to a reference point.
Example: Often we say that our school or a shop is 2 km or four km from our house. Here, our house is taken as reference point, from which distance is considered.
Motion is of many types, such as motion along a straight line, motion along a circular path, zig-jag or erratic motion, controlled motion, uncontrolled motion, Uniform motion, Non-uniform motion, etc.
Motion Along A Straight Line: When an object changes its position with time along a straight line, this is called the Motion along a Straight line. . . .