Question

Question #50b3a

Answer 1

`V=12+(-10*2)<=>`
`V=12-20m/s<=>`
`V=-8m/s`

Explanation:

If you use the law of speed in the linear uniform movement:
`V=V""_0+a(t-t""_0)`

where
`V` is the final speed
`V""_0` is the initial speed
`t` is the fianl moment
`t""_0` is the initial moment
and `a` is the acceleration

you will get:
`V=(12+g*2)m/s`
and `g=-10m/s^2` because the ball is thrown straight up
`V=12+(-10*2)<=>`
`V=12-20m/s<=>`
`V=-8m/s`