Finding magnitude of horizontal velocity

1. Nov 15, 2009

hello115897

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

A cannonball is launched horizontally from the top of a tall cliff with a horizontal speed of 45.0 m/s. The trajectory of the ball is shown in the diagram at the right. Determine the magnitude of the horizontal velocity and the vertical velocities of the cannonball after each of the 1.0 second time intervals. Use -9.8 m/s/s to calculate the values.

find horizontal velocity for t=1 second, t=2 seconds, t=3 seconds, t=4 seconds

2. Relevant equations

kinematic equations

3. The attempt at a solution
i think i would use the equation d=vit+1/2at^2
so i'd do 1/2(9.8)(1)^2
so it would be 4.9?

Last edited: Nov 15, 2009
2. Nov 15, 2009

method_man

It's minus because it is faced downward ---> vy=vy0t-(1/2)*g*t2

3. Nov 15, 2009

hello115897

im still not getting the right answer........

4. Nov 16, 2009

method_man

Ups, I'm so sorry. That was the formula for displacement-d. The formula for vertical velocity would be:
vy=-g*t.