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Contents Project 1 Perpetual Motion Machines Project 3 Siege Machines & Trebuchets Project 5 Trebuchet Improvements
Throughout the ages, people have tried to invent a machine that would keep moving forever without any help. With apparent disregard to the failure of all their predecessors, inventors and scientists are still coming up with new designs for such machines. Using an encyclopedia or the Internet, research Perpetual Motion. Find at least three designs for aperpetual motion machines. Once you have your 3 favorite designs, answer the following questions.
OPTION: DESIGN AND BUILD A MODEL OF A CLASSIC PERPETUAL MOTION MACHINE Even Leonardo Davinci had drawings of a perpetual motion machine. Some people claim that his drawings were used to explain why a machine of this type could not work. Many museums have models of perpetual motions machines that are used to show that they don’t work. Presumably these are to show would-be inventors that their ideas have been tried before. Design and build a model of a classical perpetual motion machine.
Options:
WARNING: Use extreme caution when launching rockets. Launch the rocket only in a vertical position and use a system to aim the rocket correctly during launch. Any person standing within 3 meters of the launcher should wear eye protection. Rockets should only be launched in an open field – the rocket could land anywhere within 20 meters of the launching point. If you decide to attach tail fins or a nosecone to the rocket, note that it will land with a far greater impact than it would without these enhancements. Wearing head protection is advised. OPTION 1: INTERNET RESEARCH Search the Internet to gather information on water rockets. Write an article on the different types of water rockets. Discuss the advantages and disadvantages of the different designs. OPTION 2: DESIGN AND BUILD A SODA-BOTTLE ROCKET Search the Internet to gather information on various designs for soda-bottle rockets. Design and build your own rocket launcher. Have fun! Soda Bottle Rocket Launcher There are a number of different types of soda bottle rocket launchers. A simple mechanism consists of a rubber stopper with a hole in it, a clamping device and a tube to connect the stopper to a hand pump. A valve is needed in the tube to prevent water and air escaping from the bottle before the rocket is launched.
The release pin (firing pin) is a u-shaped piece of steel wire. The release pin slides into the holes at the top of the two upper bars and holds the bottle in position by clamping on the ridge on the bottle’s neck. A piece of string is used to pull the u-shaped pin out of the holes and release the rocket. Another Design Other types of launchers are based on the fact that common 7/8" pvc pipe fits snugly in the opening of a soda bottle. The following diagram shows a design using pvc pipe:
The bottle fits over the post. The diagram does not show the clamping device or how the seal is provided to prevent leakage of water and air from the rocket while the pump is operating. Some systems use a groove in the pipe and a rubber "O"-ring to provide a seal. The right amount of plumber’s tape wound round the pipe may also work.
The study of physics is almost always aimed at making things or controlling things. Very often, people have wanted to make things that would help them to stay alive or to live longer by defending themselves or to exert power over other people. History has in some respects been shaped very much by the machines and devices that have been used for military purposes. (David’s use of a sling represented quite a departure from the traditional method of dealing with giants and changing the course of History.) Some of the early machines such as catapults and trebuchets are of particular interest and are still used for entertainment. Someone in the UK has recently built a large trebuchet that has been used to fling dead pigs, dead cows, pianos and even small motor cars over large distances. The annual "Punkin Chunkin" competition in the USA draws a number of contestants with some wonderful projectile launching devices. Early machines used two systems of storing and releasing energy: Gravitational systems and elastic potential systems. Using the Internet as a source of information,
DESIGN AND BUILD A MODEL TREBUCHET Design and build a trebuchet that is capable of hurling tennis balls, water balloons or snowballs over a distance of more that 30 feet. Using the Internet as a source, identify two or three possible designs for model trebuchets Provide or obtain diagrams /sketches of these designs. Select one of these (or your own design) that you would like to build. Give some of the main reasons for your choice of design. Provide a list of the components that will be needed and a sketch of the proposed trebuchet. Note: Throwing a water balloon is not as easy as throwing a tennis ball. Apart from being more fragile, water balloons tend to change shape as they are accelerated. They tend to "spill" out of the pouch that holds the projectile during launch. A specially designed pouch will be needed for water balloons. WARNING: If you decide to build a model trebuchet, use extreme caution when loading or launching projectiles from the device. Any person standing within 20 meters of the launcher should wear eye protection. The trebuchet should only be used in an open field – the projectile could land anywhere within 50 meters of the trebuchet – often behind the machine. Use a remote trigger – such as a pin at the end of a 2-meter piece of string. Stand at least 2 meters away from the trebuchet when launching projectiles.
Build a Model Ram Pump The purpose of this project is to show how the kinetic energy of a liquid can be converted to pressure energy. By using a low pressure to accelerate a relatively large volume of liquid, the kinetic energy of this volume of liquid can be transferred to a smaller volume of liquid. This energy is then converted to pressure energy that allows the smaller volume of liquid to be pumped to a height greater than the initial level of the liquid. A simple model involves using a soda bottle from which the bottom has been removed. Connect a one-hole stopper and tubing to the bottle as shown below. Pinch the tube at the end while filling the bottle with water. Open the tube. Let water flow from this end and stop the flow suddenly. Observe the height to which water travels from the upward-facing nozzle. Materials & Equipment Soda bottle
A trebuchet is a device that transfers energy (stored as gravitational potential energy in the weight) to the projectile. Most of the energy is converted initially to kinetic energy but the projectile does gain some gravitational potential energy before it leaves the sling. Certain factors affect the performance of a trebuchet. Some energy is used up in horizontal movement of the weight as it falls and it has been found that mounting the trebuchet on wheels helps to minimize this loss of energy. Write a Report List some of the other factors that could help to reduce the efficiency of your trebuchet. Propose changes in design that could help to eliminate these losses in efficiency. Test the effects of the modifications. Describe the effects of the changes to the design. |
