The bus departs from a stop with an acceleration of 2 m / s after what time it develops, there is a speed of 72 km / h.

If the bus moves in a straight line and evenly, then its speed can be calculated using the formula:

V = V0 + at, where V is the final speed of the bus (V = 72 km / h = 72 * 1000/3600 = 20 m / s), V0 is the initial speed of the bus (V0 = 0 m / s, the bus departed from a stop) , a is the acceleration of the bus (a = 2 m / s2), t is the travel time (s).

Let’s express and calculate the bus travel time:

V = V0 + at = 0 + at = at.

t = V / a = 20/2 = 10 s.

Answer: The bus will reach a speed of 72 km / h in 10 seconds.