E2: A runner A takes 4 minutes to travel 1 thousand (1.6 km) and a marathon runner B takes 2.25 hours to Travel 42 km. (a) Determine the average speeds. (b) How long would the Marathon if it was traveled at the speed of runner A.E16: t = 3 s, une particule se trouve en x = 7m la vitesse v? = 4 m/s. t = 7 s, elle est en x = -5 m la vitesse v? = -2 m/s. Dterminez : (a) sa vitesse moyenne ; (b) son acclration moyenne.