Define rest & motion, speed & velocity, displacement & distance, uniform & non-uniform speed & velocity, instantaneous velocity, acceleration

Kinematics is the branch of mechanics that deals with the motion of objects without considering the forces that cause the motion.

Rest and Motion: 

  • An object is said to be at rest if its position relative to its surroundings does not change over time. 
  • If its position changes, it is said to be in motion.

Speed and Velocity: 

  • Speed is a scalar quantity that measures the magnitude of an object's change in position (distance) per unit of time. 
  • Velocity is a vector quantity that includes both the speed and direction of an object's change in position.

Displacement and Distance: 

  • Displacement is a vector quantity that measures the change in position of an object from its initial to final position. 
  • Distance is a scalar quantity that measures the total length of the path taken by an object from its initial to final position.

Uniform and Non-Uniform Speed/Velocity: 

  • An object is said to have uniform speed if its speed is constant over time. 
  • An object is said to have non-uniform speed if its speed changes over time. 
  • The same applies to velocity, an object is said to have uniform velocity if both its speed and direction remain constant over time and non-uniform velocity if either its speed or direction changes over time.

Instantaneous Velocity: 

  • The velocity of an object at a specific instant in time. It can be thought of as the limit of the average velocity over a very short period of time as the time interval approaches zero.

Acceleration:

  • Acceleration is the rate of change of velocity over time, and it is a vector quantity that measures the change in the direction or magnitude of an object's velocity.