Question

Keiko is riding a skateboard 2 m/s, west. How long will it take her to reach a velocity of 8 m/s, west if her acceleration is 2 m/s2

Answer 1

Your initial velocity is 2 m/s. lets call that 'U' and your final velocity is 8 m/s. Lets call that 'V'.
a = (V-U)/t
but we are asked 't' not 'a' so the formula changes to...
t = (V-U)/a
t = (8-2)/2
t = 3 sec

Answer 2

Answer : The time taken will be 3 seconds.

Explanation :

By the 1st equation of motion,

`v=u+at` ...........(1)

where,

v = final velocity = 8 m/s

u = initial velocity = 2 m/s

t = time = ?

a = acceleration =
`2m/s^2`

Now put all the given values in the above equation 1, we get:

`8m/s=2m/s+(2m/s^2)* t`

`t=3s`

Hence, the time taken will be 3 seconds.