Question

A cannon is pointed at a 60 degree angle relative to a flat, horizontal field. It fires a projectile with a muzzle speed of 1500 ft/s. Then the gunners change the angle to 30 degree, reload the cannon, and 5.0 seconds later, fire. What is the required muzzle speed for the second projectile to hit the ground at the same time as the first? (Assume air resistance is negligible.)