Question

What is the angle between Displacement and Retardation in One Dimensional Motion??

Answer 1

In 1D, things are moving either backwards or forwards on the same straight line so there are only two possible angles: 0 degrees and 180 degrees.

Retardation is acceleration that opposes motion (otherwise known as deceleration), so it will act in the opposite direction to displacement.

Answer 2

Sounds right. Retardation implies countering the direction of motion, thus 180o out of phase.