Find initial velocity given acceleration & distance, no time

[brendonsushi]

Homework Statement

Frog jumps in air to 1m height. Neglecting air resistance find initial speed the instant it leaves the ground.
a= -9.8m/s^2
d= 1m
vi=?

Homework Equations

d=1/2(vf+vi)t
d=1/2at^2 + vi(t) + di

The Attempt at a Solution

I figured that since acceleration is 9.8m/s, I could just find time by dividing 9.8m/s by 9.8 and that would give me 1m/0.1s, but that doesn't seem quite right. I then proceeded to put the acceleration, distance, and "time" values into d=1/2at^2 + vi(t) + di, so that vi=0.9m/s^2, but I don't think I did it right. Is there any way to just find initial velocity with only acceleration and distance values?

 

[Buzz Bloom]

Hi brendon:

I think you are missing a useful equation. V² = 2 a d.

Hope this helps.

Regards,
Buzz