What is erratic motion?

Hint: Though the term is not very commonly used, many real life motions fall in this category of motion. On that note, you could think of the characteristics of a real life motion and hence the definition of erratic motion. Also, keep in mind that not all real life motions fall in this category.

Complete step-by-step solution:
An erratic motion is said to occur when any one of the motion parameters like displacement (s), velocity (v), acceleration (a),etc, is not continuous. These discontinuous functions show a jump or sharp bends. You could clearly understand the concept when these motion parameters are plotted against time. The above mentioned jump or sharp bend will be clearly observable on that plot so made.
Many of the real systems are known to show erratic motion. The real life example is a car being driven on a road. This car will start and stop, increase and decrease in speed, etc during its motion and hence is an example for erratic motion.
However, there are certain points that should be kept in mind while analyzing an erratic motion.
(1) Each continuous segment of motion should be analyzed separately.
(2) Remember the fact that the end condition of the previous segment is known to be the initial condition for the current segment.

Note: Another name for this type of motion is ‘uncontrolled motion’. This class of motion is known to be unpredictable. Take for the case of driving a car. Lots of changes in the motion parameters can be made in a journey. One could start, stop, speed up, speed down, change direction, etc. All in all erratic motions are chaotic.