# Homework Help: Kinematics Problem on trout

1. Sep 23, 2008

### whyorwhynot

Kinematics Problem (Solved)

I greatly apologize for making this my very first post. I am in great need of assistance though, and I hope someone can help me comprehend how to solve this.
It seems relatively simple, but it does not seem to be clicking in my mind at the moment.

1. The problem statement, all variables and given/known data
A trout jumps a waterfall 2.5 m high. With what minimum speed did it leave the water below to reach the top?

2. Relevant equations
Issue at hand.

3. The attempt at a solution
I understand that Vf(final) = 0 m/s, x = 2.5 m, and Vo is what I am solving for.
I have a card of equations but I'm unsure as to which would apply to this. And I don't believe gravity plays a part in this, does it?

Thank you so much for your assistance.

Last edited: Sep 23, 2008
2. Sep 23, 2008

### ak1948

Gravity does play a part. In fact it would reach the top at any speed greater than zero if it weren't for gravity.

3. Sep 23, 2008

### whyorwhynot

That makes much more sense then.
We've been using -9.8 m/s^2 in reference to falling objects though. Would this become +9.8 m/s^2 since the frog is jumping up, not down?

Thank you very much by the way!

4. Sep 23, 2008

### Mattowander

No. Gravity is ALWAYS directed downward. If you defined up as the positive Y direction, then acceleration due to gravity is going to be negative.

Hope that helps :)

5. Sep 23, 2008

### whyorwhynot

I understand it now. Thank you both so so much for your help!