In World War I, the most awesome weapons of war were huge cannons mounted on railcars. Figure shows such a cannon, mounted so that it will project a shell at an angle of 30°. With the car initially at rest, the cannon fires a 200-kg projectile at 125 m/s. Now consider a system composed of a cannon, shell, and railcar, all rolling on the track without frictional losses.

(a) Will the total vector momentum of that system be the same (i.e., "conserved") before and after the shell is fired? Explain your answer in a few words.

(b) If the mass of the railcar plus cannon is 5000 kg, what will be the recoil velocity of the car along the track after the firing?

(c) The shell is observed to rise to a maximum height of 180 m as it moves through its trajectory. At this point, its speed is 80 m/s. On the basis of this information, calculate the amount of thermal energy produced by air friction on the shell on its way from firing to this maximum height.

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30°