Building A Steam Powered Boat

Building a Steam Powered Boat
A lesson in thermodynamics Subject: science Grade: 9-12 Time required: one class period Content standards: Grades 9-12: Physics 1b, 2c, 2e, 2f, 2h, 3a-g Key concepts:  A transfer of heat energy occurs when substances having different temperatures are allowed to mix.  A heat engine, such as a steam turbine, is a device that converts heat energy into mechanicalwork.  The quantity of heat transferred to a system is equal to the work done by the system plus the change in the internal energy of the system (total amount of energy remains constant). This is called the Law of Conservation of Energy, or First Law of Thermodynamics.  Whenever two substances at different temperatures are allowed to mix, heat travels from the hotter substance to the colder one. Thequantity of heat given off by the hotter substance is equal to the quantity of heat energy gained by the cooler object, provided that heat energy does not escape to the surroundings. The transfer of energy will continue in this way until both substances reach the same temperature. This is called the Principle of Heat Exchange.  heat energy lost = heat energy gained   EH (lost) = EH (gained)Background Information: Laws of Thermodynamics Energy exists in many forms, such as heat, light, chemical energy, and electrical energy. Energy is the ability to bring about change or to do work. Thermodynamics is the study of energy. The First Law of Thermodynamics states that energy can be changed from one form to another, but it cannot be created or destroyed. The total amount of energy andmatter in the Universe remains constant, merely changing from one form to another. The First Law of Thermodynamics (Conservation) states that energy is always conserved, it cannot be created or destroyed. In essence, energy can be converted from one form into another. The Second Law of Thermodynamics states, "in all energy exchanges, if no energy enters or leaves the system, the potential energy ofthe state will always be less than that of the initial state." This is also commonly referred to as entropy. A spring-driven watch will run until the potential energy in the spring is converted, and not again until energy is reapplied to the spring to rewind it. A car that has run out of gas will not run again until you walk ten miles to a gas station and refuel the car. Once the potential energylocked in carbohydrates is converted into kinetic energy (energy in use or motion), the organism

will get no more until energy is input again. In the process of energy transfer, some energy will dissipate as heat. Entropy is a measure of disorder: cells are not disordered and so have low entropy. The flow of energy maintains order and life. Entropy wins when organisms cease to take in energy anddie. Introduction: Building a simple heat engine Heat engines take many forms, from the internal combustion engine in the family car to giant boilers that make steam to spin the giant turbines that generate electricity for our homes. What they have in common is they steal some of the energy moving between something hot and something cold, and convert it into motion. When you heat a gas like airor steam, the molecules in the gas move around faster. The faster they move, the harder they hit anything that is in the way. If we put something in the way, such as a propeller or a pinwheel, we can make them spin (this is how turbine generators spin to create electricity). If we confine the gas in a container with a lid, we can pop the lid off (this is how the piston in a car engine works). If welet the fast moving molecules push on one side of a container, and escape through a small hole on the other side (so they are pushing on one side more than on the other) then we have a rocket or a jet, which moves in a direction away from the side with the hole. Materials: 1. 13-15 inches of copper tubing (1/8 diameter), for each group of 2-3 students (You can use the easier to find 1/4 inch...