# Jumping Flea - Simple Kinematics

1. Sep 22, 2009

### JG89

1. The problem statement, all variables and given/known data

A flea jumps straight up to a maximum height of 0.53 m. What is its initial velocity as it leaves the ground?

2. Relevant equations

3. The attempt at a solution

Okay, I have three kinematic equations for constant acceleration I can use. All of them require the knowledge of some time interval, except for one, so I shall use that one since I'm not given any time info in this question.

The equation says: $${v_f}^2 = {v_i}^2 + 2a_s(s_f - s_i)$$. Obviously f denotes final and i denotes initial.

I know that my final velocity will have to be 0 since if the flea jumps to a maximum height of 0.53 m, he will start coming down after that. I also know that $$a_s = -9.8$$. Also, $$s_i = 0$$ and $$s_f = 0.53$$.

Thus I have $$0 = {v_i}^2 - 2(9.8)(0.53) \Leftrightarrow \sqrt[]{2(9.8)(0.53)} = v_i$$ and I will take the positive root to be my v_i.

Is this correct?

2. Sep 22, 2009

### rl.bhat

Yes. It is correct.