The Science

The mortar came into its own during World War One. Normal artillery had a very flat trajectory and wasn't able to land inside narrow enemy trenches. The mortar has a lobbing firing arc – it went almost straight up and straight down, making it ideal for trench warfare.

The teams had to change the angle of their mortars on the vertical plane to get the correct range and use lateral aiming to make sure their shots fell on the paddling pool targets. The energy they could get into the ammo was also very important – more energy meant more range.

The Bus Boys' mortar relied on the potential energy stored in the tensioned kicking arm. After their machine had broken they could get much less tension into the kicking arm and so their ability to hit at longer range suffered.

Woof Justice's ammo was pressed up against the cage doors held on the end of the spinning arm. The mortars wanted to escape because centrifugal force directs away from the axis of rotation. Once the doors were opened by the catch the ammo flew out. Because of where they put the catch the balls were released on the same vertical angle each time, with range controlled by adding more or less speed to the spinning arm, which was powered by a moped engine.

You can see the effect of centrifugal force on amusement park rides where a spinning cage pushes riders against the wall, holding them up above the floor. At home you can see the force acting on the clothes in a washing machine – on a fast spin they are forced against the side of the drum.

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