Question

give difference acceleration and retardation

Answer 1

Accelaration and deceleration are vector quantities and only difference between them is direction. .for example if car is speeding up then it means that positive acceleration is occurring i.e in the direction of velocity which is simply called accelaration . Now if car is slowing down then car has negative acceleration i.e in direction opposite to velocity which also deceleration . Accelaration is actually vector quantity . Positive acceleration is simply called accelaration while negative acceleration is called deceleration

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Answer 2

Retardation is negative of acceleration.

suppose,
if velocity of a body increasing@5m/s^2 then acceleration be 5....

But if velocity is decreasing with same rate then acceleration be -5

So, to avoid this -ve sign we simply say -ve acceleration is retardation.