Question

Question #6e1a6

Answer 1

`8.5 \ "m/s"`

Explanation:

Using the kinematics equation, `v=u+at`

We got: `v=21.4 \ "m/s", a=0.86 \ "m/s"^2, t=15 \ "s"`, so we get

`21.4 \ "m/s"=u+0.86 \ "m/s"^2*15 \ "s"`

`21.4 \ "m/s"=u+12.9 \ "m/s"`

`u=21.4 \ "m/s"-12.9 \ "m/s"`

`u=8.5 \ "m/s"`