What is retardation?

A car moving along a straight highway with a speed of 126 kilometre per hour is brought to a stop within a distance of 200m. What is the retardation of the car (assumed uniform) and how long does it taken for the car to stop?

What is variation? What are its types?

A bus is moving with the initial velocity of 'u' m/s. After applying the breaks, its retardation is 0.5 m/ s^(2) and it stoped after 12s. Find the initial velocity (u) and distance travel by the bus after applying the breaks.

What is heparin? What is its use?

What are the glands present related with the eyes? What is it function?