The body passed the first 500 m at a speed of 36 km / h, then 300 m at a speed of 15 m / s.

| January 17, 2021 | education

The body passed the first 500 m at a speed of 36 km / h, then 300 m at a speed of 15 m / s. the last part of the way it passed at a speed of 20 m / s. how long did the body move if the entire path is 1 km?

S1 = 500 m.

V1 = 36 km / h = 10 m / s.

S2 = 300 m.

V2 = 15 m / s.

V3 = 20 m / s.

S = 1 km = 1000 m.

t -?

The travel time of the entire path t will be the sum: t = t1 + t2 + t3, where t1 is the time of the first part of the path, t2 is the time of the second part of the path, t3 is the time of the third part of the path.

t1 = S1 / V1.

t1 = 500 m / 10 m / s = 50 s.

t2 = S2 / V2.

t2 = 300 m / 15 m / s = 20 s.

t3 = S3 / V3.

S3 = S – S1 – S2.

S3 = 1000 m – 500 m – 300 m = 200 m.

t3 = 200 m / 20 m / s = 10 s.

t = 50 s + 20 s + 10 s = 80 s.

Answer: the body moved all the way for a time t = 80 s.



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