A trolley moving eastward experiences a uniform acceleration of −2m/s2 for 7s and its final speed becomes 4m/s.
a. (i) Write the mathematical relation that connects acceleration with initial velocity, final velocity and time for motion along a straight line.
b. (ii) Using the given data, determine the initial speed of the trolley.
c. (iii) Explain whether the trolley is speeding up or slowing down during this interval and support your answer with the sign of acceleration.