Question

What do you mean by motion in one direction?

Answer 1

motion in 1 dimension means ONLY ONE out of x-axis, y-axis or z axis changes with time

which means
a body continues to move in only one direction (without changing direction)..

for example:-
a body continues to move in a straight line without turning represents 1 dimension motion......
cause if it turns it will have 2 dimension motion..(i.e. 2 out of x-axis, y-axis or z axis will change)
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