The boat sails the first quarter of the way at a speed of 15 m / s and the remaining 180 m

| March 20, 2021 | education

The boat sails the first quarter of the way at a speed of 15 m / s and the remaining 180 m takes 20 s, find the average speed of the boat along the entire path.

V1 = 15 m / s.

S2 = 180 m.

t2 = 20 s.

S1 = S / 4.

S1 + S2 = S.

Vav -?

To find the average speed of movement Vav, it is necessary to divide the entire distance traveled by the boat S by the time of its passage t: Vav = S / t.

The travel time of the entire path is expressed by the sum: t = t1 + t2, where t1 is the time of movement on the first part of the path, t2 is the time of movement on the second part of the path.

t1 = S1 / V1 = S / 4 * V1.

S = S1 + S2 = S / 4 + S2.

3 * S / 4 = 180 m.

S = 240 m.

S1 = 60 m.

t1 = 240 m / 4 * 15 m / s = 4 s.

Vav = 240 m / (4 s + 20 s) = 10 m / s.

Answer: the average boat speed is Vav = 10 m / s.



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