**Answer:**

6.67 meters/second

or equivalently

24 km/hour

**Step-by-step explanation:**

The relationship between final velocity, initial velocity, acceleration and time is given by the equation

v = u + at

where

v = final velocity

u = initial velocity

a = acceleration

t = time from initial velocity to final velocity

We are given

v = 78 km/h

a = 0.25 m/s²

t = 1 minute

We are asked to find u, the initial velocity

Since each of the parameters are given in different units, the first step is get them all to a common unit

Let's convert everything to m/second and seconds

Since there are 1000 meters in 1 km and 3600 seconds in 1 hour ,

78 km/hour = 78 x 1000/3600 = 21.66667 meters per second which would be our value for **v**. Rounded to 2 decimals this would be 21.67 m/s

There are 60 seconds in 1 minute so our value for **t** = 1 minute x 60 = 60 second.

We finally have

**v = 21.67 m/s**

**a = 0.25 m/s²**

**t = 60 seconds**

Plug in known values in the equation

21.67 = u + 0.25 x 60

21.67 = u + 15

u + 15 = 21.67

u = 21.67 - 15 = 6.67 m/s

If you want to convert this back to km/hour multiply by 3600 and divide by 1000

u = 6.67 x 3600/1000 = 24.012 km/hour or rounded to 24 km/hour