The speed of a vehicle driving with a constant acceleration of 0.5 m / s increases from 72 km / h

| February 4, 2021 | education

The speed of a vehicle driving with a constant acceleration of 0.5 m / s increases from 72 km / h to 108 km / h. How long did the car take to change the speed?

V0 = 72 km / h = 20 m / s.

V = 108 km / h = 30 m / s.

a = 0.5 m / s ^ 2.

t -?

Let’s convert the units of measurement of speed into units of the International System of SI.

1 km = 1000 m, 1 h = 60 min = 3600 s.

V0 = 72 km / h = 72 * 1000 m / 3600s = 20 m / s.

V = 108 km / h = 108 * 1000 m / 3600s = 30 m / s.

According to the definition, the acceleration of a body a shows how quickly the speed of movement of the body changes and is determined by the formula: a = (V – V0) / t, where V, V0 are the final and initial speed of movement, t is the time during which the speed changes.

t = (V – V0) / a.

t = (30 m / s – 20 m / s) / 0.5 m / s ^ 2 = 20 s.

Answer: the speed changes during t = 20 s.



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