Answer:
[tex]v_{avg} = 40 km/h[/tex]
Explanation:
Time taken by the car to move first 40 km distance
[tex]t_1 = \frac{d}{v}[/tex]
here we have
[tex]t_1 = \frac{40}{30}[/tex]
similarly the time taken by car to move next 40 km is given as
[tex]t_2 = \frac{40}{60}[/tex]
so total time of the motion is given as
[tex]t = t_1 + t_2[/tex]
[tex]t = \frac{40}{30} + \frac{40}{60}[/tex]
[tex]t = 2 hours[/tex]
total distance moved by the automobile
[tex]d = 40 + 40 = 80 km[/tex]
so the average speed is given as
[tex]v_{avg} = \frac{distance}{time}[/tex]
[tex]v_{avg} = \frac{80 km}{2 hr}[/tex]
[tex]v_{avg} = 40 km/h[/tex]
