Calculating Work for a Fired Projectile

[superaznnerd]

Homework Statement

a 4kg projectile is fired on Earth with intiial velocity 40m/s at an angle of 30 degrees to the horizontal. what work was done in firing the projectile?

Homework Equations

The Attempt at a Solution

I got 5542 J. Answer is suppsoedly 3200J

 

[rock.freak667]

The work done is the change in kinetic energy. The mass goes from 0 to 40 m/s. So the change in kinetic energy is?