A girl is riding a bicycle at a constant velocity of 3.0 m s⁻¹ along a straight road. At time t = 0, she passes her brother sitting on a stationary bicycle. At time t = 0, the boy sets off to catch up with his sister. His velocity increases from time t = 0 until t = 5.0 s, when he has covered a distance of 10 m. He then continues at a constant velocity of 4.0 m s⁻¹.
a. Draw the displacement–time graph for the girl from t = 0 to t = 12 s.
b. On the same graph axes, draw the displacement–time graph for the boy.
c. Using your graph, determine the value of t when the boy catches up with his sister.