In the year 2040, society has broken down and you live in a small com- munity trying to defend itself from possible invaders. Your community’s cannon was recently damaged and is now stuck to a launch angle of 30 degrees above the hori- zontal. The cannon is perched atop a 5-m high wall that surrounds your community. Invaders are approaching in a tank, very slowly making forward progress through muddy terrain and man-made obstacles (that serve as distance indicator) What launch speed should you set your cannon to, when the tank is near the 500-m mark?
