A gun in a World War II battleship could shell targets 12 km away. Find the minimum launch speed needed to achieve that range. Give your answer in m/s.  

During World War I, the Germans had a gun called Big Bertha thatwas used to shell Paris. The shell had an initial speed of 0.741km/s at an initial inclination of 69.3? to the horizontal.
The acceleration of gravity is 9.8 m/s2 . How far away did theshell hit?
Answer in km.

How long was it in the air?
Answer in units of s.

Problem 7.76
The barrels of the 16- guns (bore diameter = 16 = 41 ) on the WorldWar II battleship U.S.S. Massachusetts were each 15 long. Theshells each had a mass of 1300 and were fired with sufficientexplosive force to provide them with a muzzle velocity of 760 . Usethe work-energy principle to determine the explosive force (assumedto be a constant) that was applied to the shell within the barrelof the gun. Express your answer in both (a) newtons and (b) inpounds.

The barrels of the 16-in guns (bore diameter = 16in = 41cm ) on theWorld War II battleship U.S.S. Massachusetts were each 15m long.The shells each had a mass of 1400 kg and were fired withsufficient explosive force to provide them with a muzzle velocityof 740m/s . Use the work-energy principle to determine theexplosive force (assumed to be a constant) that was applied to theshell within the barrel of the gun. Express your answer in both (a)newtons and (b) in pounds.
I worked part a and got it wrong. My answer was 35000 N or whenrounded to 2 significant figures, but it is wrong. Please solve allthe way through for both a and b.