Question

Which of the following is an example of three dimensional motion?
A) Motion of a train on a straight railway track
B) Motion of an aeroplane
C) Motion of a billiard ball on the billiard table
D) All of the above.

Answer 1

Hint: One dimensional motion is concerned with the objects moving in a straight line only. Similarly two dimensional motion is concerned with the objects moving in 2 dimensions or on a plane. Three dimensional motions are in three dimensions. They are described with equations using three spatial variables and one time variable.

Complete step by step solution:
One dimensional motion describes the motion of objects moving in straight lines. When any particle's velocity changes with time, then that particle/object is said to be accelerating. When restricted to one dimension, there are only two possible directions for the velocity and acceleration that is forward and backward. Since motion of a train on a straight line is the same motion as that in one dimension therefore option A is not an example of three dimensional motion.

Hence option (A) is incorrect.

Motion of an aeroplane, an aeroplane travels in the following dimensions:
i) It travels to and forth while on runway this makes first dimension
ii) It also travels in a plane when it takes turns on runway, second dimension
iii) And when it flies it travels in the third dimension.
As the aeroplane travels in three dimensions, hence it is an example of three dimensional motion.

Therefore, Option (B) is the correct option.

Motion of billiards is limited to a plane only as the balls don’t travel in upward or downward direction in any legal manner.

Hence option (C) is also an incorrect option.

Note: Do remember that in three dimensional motion, the motion is described using three spatial variables and one time variable. Movement of gyroscope is an example of three dimensional motion. Motion in space incorporates all the X, Y and Z axes. Motion of birds flying in the sky is also an example of three dimensional motion.