Deceleration also known as retardation or negative acceleration, is the acceleration acts in the opposite direction of motion and is responsible for reducing the velocity of a body.
If, u = initial velocity v = final velocity a = constant deceleration t = time taken and s = displacement Then equations of motion is given by: v = u - at s = ut - ½ at^{2} v^{2} = u^{2} - 2as
SI unit of deceleration is m/s^{2}.
Example: An object moving with a velocity of 40m/s is brought to rest in 8 seconds by a constant deceleration. Find the deceleration applied.
Ans: Here, initial velocity(u) = 40m/s Final velocity(v) = 0 m/s Deceleration = a Time = 8 s From 1st equation of motion: v = u - at 0 = 40 - a.8 a = 40/8 = 5 m/s^{2}.
Question: If an object is accelerated from rest with an acceleration of 2 m/s^{2} for 10s, How much deceleration is needed to bring the object to rest in 4s.