Motion

Defining Motion

  • Motion is defined as a change in position of an object with respect to its surroundings in a given period of time.
  • Motion is mathematically described in terms of displacement, distance, velocity, acceleration, time, and speed.
  • The types of motion include translational, rotational, periodic, and non-periodic.

Distance and Displacement

  • Distance refers to the total path length covered by an object in motion. It is a scalar quantity.
  • Displacement is the shortest straight line distance from the initial to the final position of an object, and is a vector quantity.
  • When the motion of an object is along a straight line, the distance travelled and the magnitude of the displacement are the same.

Speed and Velocity

  • Speed is defined as the rate of change of distance. It is a scalar quantity.
  • Velocity is defined as the rate of change of displacement. It is a vector quantity.
  • Average speed is found by dividing the total distance traveled by the total time.
  • Average velocity is found by dividing the total displacement by the time taken.

Acceleration

  • Acceleration refers to the rate of change of velocity of an object with respect to time.
  • It is a vector quantity, as it has a direction associated with it.
  • The unit of acceleration is m/s².
  • An object accelerates if its velocity changes either in magnitude or in direction or both.

Uniform and Non-uniform Motion

  • An object in uniform motion travels equal distances in equal time intervals.
  • An object in non-uniform motion travels unequal distances in equal time intervals.
  • An object traveling with constant velocity is said to be in uniform motion.

Equations of Motion

  • First equation of motion: Final velocity (v) = Initial velocity (u) + (Acceleration (a) x Time (t)).
  • Second equation of motion: Displacement (s) = Initial velocity (u) x Time (t) + 0.5 x Acceleration (a) x (Time (t)²).
  • Third equation of motion: Final velocity² (v²) = Initial velocity² (u²) + 2 x Acceleration (a) x Displacement (s).
  • These equations are applicable only under the condition of uniform acceleration.