## Essential University Physics: Volume 1 (4th Edition)

a) When it moves this speed for half the total time, its average speed is the average of the velocities. Thus: $v = \frac{v_1+v_2}{2}$ b) We know that half the total distance equals $\frac{L}{2}$. Thus, we find: $v=\frac{L/2+L/2}{\frac{L/2}{v_1}+\frac{L/2}{v_2}}$ Thus, we find: $v= \frac{2v_1v_2}{v_1+v_2}$ c) The average speed is greater in case a).