# Kinematics in two demensions

1. Oct 7, 2004

### charvonne coates

I have several similair questions like this but i dont know where to start? Mabey iam using the wrong equation > d=vnaught(t)+1/2at^2

one of the questions states that a tennis ball is struck such that it leaves the racket horizontally with a speed of 29.5m/s. The ball hits the court at a horizontal distance of 20.6m from the racket. What is the height of the tennis ball when it leave the racket.

I know iam looking for the distace, do i find time and then solve the above equation and if so how do i go about solving for time?

2. Oct 7, 2004

### arildno

OK, when in doubt about which equations to use in kinematics, go back to the basics!!
And that is: NEWTON'S 2.LAW OF MOTION!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
So, can you set up F=ma, both the horizontal equation of motion, AND the vertical equation of motion?

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