9709 P42 - Jun 2016 - Q4
3365
A sprinter runs a race of 400 m. His total time for running the race is 52 s. The diagram shows the velocity-time graph for the motion of the sprinter. He starts from rest and accelerates uniformly to a speed of 8.2 m/s in 6 s. The sprinter maintains a speed of 8.2 m/s for 36 s, and he then decelerates uniformly to a speed of V m/s at the end of the race.
(i) Calculate the distance covered by the sprinter in the first 42 s of the race.
\((ii) Show that V = 7.84.\)
(iii) Calculate the deceleration of the sprinter in the last 10 s of the race.
