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
