Moving along the route, the group of tourists covered the path s1 = 4 km for the time interval t1 = 0.8 h

Moving along the route, the group of tourists covered the path s1 = 4 km for the time interval t1 = 0.8 h, then rested for t2 = 0.7 h. The path s2 = 2 km, which remained, she covered in the time interval t3 = 0.5 hours. Determine the average speed of the group along the entire route.

s1 = 4 km = 4000 m.

t1 = 0.8 h = 2880 s.

t2 = 0.7 h = 2520 s.

s2 = 2 km = 2000 m.

t3 = 0.5 h = 1800 s.

Vav -?

To find the average speed of movement of the group along the entire path Vav, it is necessary to divide their entire path S by the time of its passage t: Vav = S / t.

The entire path of movement of the group S will be the sum: S = s1 + s2, where s1, s2 are the paths of the first and second parts of the path.

S = 4000 m + 2000 m = 6000 m.

The travel time t will be the sum: t = t1 + t2 + t3, where t1, t3 are the travel times of the first and second sections of the path, t2 is the rest time of the group.

t = 2880 s + 2520 s + 1800 s = 7200 s.

Vav = 6000 m / 7200 s = 0.83 m / s.

Answer: the average speed of a group of tourists was Vav = 0.83 m / s.