Velocity
The velocity of an object can be defined as the rate of change of the object’s position concerning a frame of reference and time. The displacement is a vector quantity, with both an associated magnitude and direction. The SI unit is a meter per second (m/s). The velocity of an object can be positive, negative or even zero. If there is a change in magnitude or the direction in the velocity of a body the body is said to be accelerating.
Initial velocity describes the pace with which any object travels when gravity first applies force on the object, whereas, the final velocity is a vector quantity that describes the commodities of the speed and direction of a body in motion once it has reached its maximum acceleration.
Speed and Velocity
Mechanics can be termed as the branch of physics concerned with the concepts of energy and forces and their effect on bodies. It governs the relationships related to the motion of objects, that is, between matter, force, and its associated energy. It is responsible for the motion of bodies and the action of forces on these bodies as well. Practically, mechanics involve the design, construction, or operation of machines or tools. For instance, the distance covered by a car to stop travelling at a speed of 30 km/h.
The branch of classical mechanics concerned with the motion of points, object groups and systems, holding no reference to the motion of these objects, is called Kinematics, often termed the “Geometry of Motion.”
The sub-branch of physical science which is related to the motion of material objects under the effect of the physical factors affecting them, that is force, mass, momentum, and energy is called the Dynamics.
Rest
Anybody is said to be at a rest position if there is no change in its position (distance, displacement) with time, concerning its surroundings or a reference point.
Motion
The change in the position of anybody concerning time can be termed as motion. Any object under motion can be visualized by the naked eye by determining the change in the positional coordinates and then, associating it through the eye of the arbitrary observer. Motion can be computed in terms of both the position vectors, that is, the displacement, and distance, and taking into consideration the speed factors, that is, velocity, acceleration, speed, and time.
For instance, a spring ball attached to one end of a rod swinging at different time frames can be assumed to be in motion.