Homework Help: Initial Velocity question

1. Sep 9, 2007

chemguy990

A ball of unknown mass is thrown straight up.

*maximum height reached in 5.78 seconds
*acceleration due to gravity 9.8 m/s2

Calculate initial velocity in m/s

Would the initial velocity be 9.8 m/s2 x 5.78 s: 56.644 m/s?

Thats all the information given.

2. Sep 9, 2007

rocomath

that's what i got

$$v_y=v_{0y}+gt$$

$$-v_{0y}=gt$$

3. Sep 9, 2007

Inonin

Not to be redundant with the other post but i got the same=P

V initial x (Acceleration)(time) = V final

At the highest point, the velocity is 0 so

V initial + (-9.8m/s^2)(5.78s) = 0

V initial = 56.644 m/s

4. Sep 9, 2007

rocomath

no prob :) so that's 3 for 56.644 m/s!