The average speed is the ratio between the total space and the total time of the motion: [tex]v= \frac{S_{tot}}{t_{tot}} [/tex] The total space is [tex]S_{tot}=63 km + 56 km = 119 km [/tex] while the total time is [tex]t_{tot}=2h+3h = 5h[/tex] So, the average velocity is [tex]v= \frac{119 km}{5 h} =23.8 km/h
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We can also rewrite it in m/s. The total space is [tex]S_{tot}=119000 m[/tex], while the time is [tex]t_{tot}=5h\cdot 3600 s/h = 18000s[/tex], and so [tex]v= \frac{119000m}{18000s}=6.6 m/s [/tex]
