For the first 2 hours the car moved at a speed of 30 km / h, for the next 1 hour it stood still, and then for 3

| June 18, 2021 | education

For the first 2 hours the car moved at a speed of 30 km / h, for the next 1 hour it stood still, and then for 3 hours it moved at a speed of 60 km / h. Determine the average speed of the car along the way.

t1 = 2 h.

V1 = 30 km / h.

t2 = 1 h.

t3 = 3 h.

V3 = 60 km / h.

Vav -?

To determine the average speed of movement Vav, it is necessary to divide the entire path S traversed by the body by the time of its passage t: Vav = S / t.

The entire path S traveled by the car and the time of movement will be expressed by the formulas: S = S1 + S2 + S3, t = t1 + t2 + t3.

Vav = (S1 + S2 + S3) / (t1 + t2 + t3).

S1 = V1 * t1.

S1 = 30 km / h * 2 h = 60 km.

Since t2 = 1 h the car was parked, S2 = 0 km.

S3 = V3 * t31.

S3 = 60 km / h * 3 h = 180 km.

Vav = (60 km + 180 km) / (2 h + 1 h + 3 h) = 40 km / h.

Answer: the average vehicle speed is Vav = 40 km / h.



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