• Distance

    Distance travelled by a body is the actual length of the path covered by it irrespective of the direction in which the body travels. Distance is a scalar quantity which requires only magnitude but no direction to explain it. For example, Ramesh travelled 65 km. Distance is measured by odometer in vehicles.

     

    Displacement

    Displacement of a body is the shortest (straight line) distance between its initial position and final position along with direction. Displacement is a vector quantity requiring both magnitude and direction for its explanation. For example, suppose Ramesh travelled 4m towards the east from its initial position then 3m towards the north. In this example, displacement is 5m in the direction shown by the red arrow.

    Displacement can be zero (when the initial point and final point of the motion are same). For example, circular motion.

     

    Difference between Distance and Displacement

    Distance        Displacement
    It is an actual path length travelled by an object. It is a shortest path length between the initial point and the final point of an object.
    It is a scalar quantity. It is a vector quantity.
    It remains positive, can’t be ‘0’ or negative. It can be positive (+ve), negative (-ve) or zero.
    Distance can be equal to displacement (in a linear path). Displacement can be equal to distance or it's lesser than distance.

     

    Consider the motion of an object moving along a straight path. The object starts its journey from O which is treated as its reference point. Let A, B and C represent the position of the object at different instants. At first, the object moves through C and B and reaches A. Then it moves back along the same path and reaches C through B.

    Here, Distance covered by the object = Total path length covered by the object = OA + AC = 60 km + 35 km = 95 km. While, Magnitude of displacement of the object = Shortest path length between O & B  = OB  =  35 km. Thus, the magnitude of displacement (35 km) is not equal to the path length (85 km).