Through these tactics he not only foiled all the enemy's attacks, both those made at long range and any attempt at hand-to-hand fighting, but also caused them heavy losses." Behind each of these and inside the walls were stationed archers with rows of so-called 'scorpions', a small catapult which discharged iron darts, and by shooting through these embrasures they put many of the marines out of action. He had had the walls pierced with large numbers of loopholes at the height of a man, which were about a palm's breadth wide at the outer surface of the walls.
But when they had almost reached the shore, and were therefore too close to be struck by the catapults, Archimedes had devised yet another weapon to repel the marines, who were fighting from the decks. In the end Marcellus was reduced in despair to bringing up his ships secretly under cover of darkness. Then, as the distance decreased and these weapons began to carry over the enemy's heads, he resorted to smaller and smaller machines, and so demoralized the Romans that their advance was brought to a standstill. But Archimedes had constructed artillery which could cover a whole variety of ranges, so that while the attacking ships were still at a distance he scored so many hits with his catapults and stone-throwers that he was able to cause them severe damage and harass their approach. This was the siege equipment with which the Romans planned to assault the city's towers. Use this equation to determineHow you are going to fire your projectiles!!!The momentum equation can help us to think about how a change in one of the two variables might affect the momentum of an object."5. Physics Concepts to help you build your catapultMomentumĭefinitionAll objects have mass so if an object is moving, then it has momentum - it has its mass in motionĭependant variables: how much stuff is moving, how fast the stuff is movingEquationmomentum of an object is equal to the mass of the object times the velocity of the object.Momentum = mass You should have gotten an ideaabout how you are going to Structure your catapult by now…Use these concepts to youradvantage.We are going to learn about momentum next and this would help you with the concepts on firing your projectile We think of all the mass as being concentrated at the centre of mass.Ĭentre of massLine ofactionPivotF All objects have a point at which they balance, called the centre of mass. Therefore…Principle of Moments: If the clockwise moment = anticlockwise moment, the system is in equilibriumĪnticlockwiseClockwise2dd2FPivotF ĪnticlockwiseClockwise1.8 m0.8 mFPivot 40 N Ĭentre of MassIn Physics we find it a lot easier to think of objects as point masses. What force must he apply? AnswerQuestion 2 How can the force applied be reduced?Answer A motorist has to undo the nut with a wheel wrench which is 0.40 m long. Worked ExamplesQuestion 1 A wheel nut is tightened to a moment of 100 Nm. look at the picture: PerpendiculardistanceLine of action of forcemoment (newton metre, Nm) = force (newton, N)× perpendicular distance (metre, m) Physics Concepts to help you build your catapultThe Turning Effects of Forces Building a catapult:Physics Prior Knowledge Recapīuilding a Catapult: Physics Prior Knowledge Recap Physics Concepts:Turning Effects of ForcesMomentumīefore embarking on your journey for survival…
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