Read the following situation and answer the questions that follow.
A cyclist is moving due east along a straight road. At one instant her speed is 6m/s. Two seconds later, her speed has decreased to 2m/s, still towards the east.
(i) Define acceleration.
(ii) Distinguish between velocity and acceleration in a single sentence each.
(iii) If the eastward direction is taken as positive, explain whether the acceleration of the cyclist during these two seconds is positive or negative. Give a clear reason based on the change in velocity.