Projectile Motion + Kinematics Clown Problem

[Cameron1919]

Homework Statement

"a clown is shot of a cliff of height H at an angle theta and speed v. At the base of the cliff his friends are in a clown car. They start accelerating from rest one second after he is shot from the cannon. Assuming their car has constant acceleration, what is the acceleration in terms of the other variables if they catch their friend?"2. Homework Equations [/B]
How should I go about approaching this problem, knowing that the time is going to be altered in order to incorporate the total distance?

The Attempt at a Solution

http://imgur.com/69iqAif

 

[haruspex]

Homework Statement

"a clown is shot of a cliff of height H at an angle theta and speed v. At the base of the cliff his friends are in a clown car. They start accelerating from rest one second after he is shot from the cannon. Assuming their car has constant acceleration, what is the acceleration in terms of the other variables if they catch their friend?"2. Homework Equations [/B]
How should I go about approaching this problem, knowing that the time is going to be altered in order to incorporate the total distance?

The Attempt at a Solution

http://imgur.com/69iqAif

Please do not post working as images. Almost always hard to read, and impossible to point to specific lines to make comments.

Choose a definition of t=0. If you take it as the time the clown is fired, and the car accelerates at rate a, what is the position of the car at time t? (It only has to be correct for t>1.)