A car moves along a straight road so that its displacement from a fixed milestone at time t seconds is given by
s(t)=5t3−18t2+12t+20 metres.
Answer the following questions based on this model.
(i) Find an expression for the instantaneous velocity v(t) of the car.
(ii) Calculate the average velocity of the car during the time interval t=2s to t=4s.
(iii) Determine the instantaneous velocity at t=4s.
(iv) Compare the answers obtained in parts (ii) and (iii). What does this tell you about the motion of the car in this interval?
(v) State the physical units of the instantaneous velocity function v(t).