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.