Kinematic Concepts - Mission KC2 Detailed Help

Grandma Henderson challenges Michael Johnson in the 400-meter dash. Grandma H spins her wheelchair wheels five times and gives up 15 meters from the starting line. MJ makes a complete circle around the track and stops at the starting line. In this race, ____.


 
Definition of Displacement:
The displacement of a moving object is the overall change in position of the object.

 
Definition of Distance:
The distance traveled by a moving object is simply the amount of ground which is covered during the motion.


 

Displacement describes how far out of place an object is when comparing its initial and final positions. Displacement is a vector quantity which is always conscious of the direction of motion and any changes in that direction. Distance is a scalar quantity which is ignorant of the direction of travel and any changes in direction.

Suppose that a person walks 12 meters, east and then 4 meters, west. The distance traveled is 16 meters. The fact that there was a direction change is irrelevant to any measurement of the distance. The displacement of the object is 8 meters, east. The fact that there is a direction change must be considered when measuring the displacement. Displacement must account for the fact that the 4 meter segment of the motion was in the opposite direction as the 12 meter segment. For the displacement measurement, the 4 meters is considered as a negative (a directional adjective) and added onto the +12 meters.


 
If a person does a round-tripmotion and finishes at the starting position, then that person does not experience any overall change in position. Overall, the person has not been displaced or moved out of place when considering the initial and the final position. While the person may have a large distance of travel - moved over a lot of ground, there is no overall displacement or change in position.