Heat Transfer and Thermodynamics Exam Questions with Complete Solutions

Know the principle of conservation of energy and apply it to energy transfers - ANSWER-Energy cannot be created nor destroyed, it however be converted to a different form. Law of Conservation of Energy (also known as First Law of Thermodynamics) - ANSWER-in the middle of the 19th century, it was proposed by the English and German scientists that the total energy in the universe is constant. Essentially, energy cannot be created nor destroyed. Energy can, however, by converted from one form to another. The total amount of energy stays the same. There are five different forms of energy present in the universe: - ANSWER-mechanical (associated with the motion), heat, chemical, electromagnetic, and nuclear. Examples of Energy Transfer: - ANSWER-A car engine burns fuel. This converts the fuel's chemical energy into mechanical energy in order to make the car move. Windmills changes wind's energy into mechanical energy to turn turbines, which then produce electricity. Solar cells changes the sunlight, which is radiant energy, into electrical energy. Potential Energy - ANSWER-this type of energy has not yet been used. Kinetic Energy - ANSWER-an object is considered to have kinetic energy if it has mass and is in use or in motion. The formula for kinetic energy is: KE= 1/2mv2 Example of Kinetic Energy - ANSWER-A tank of gasoline has potential energy that is converted to kinetic energy by the engine. Discuss how the transfer of energy as heat is related to changes in temperature - ANSWER-Simply put, heat will naturally move from high to low temperatures. The region you find the higher temperature in is called the heat source. The region with lower temperature is called the heat sink. Heat and temperature are both measures of energy. - ANSWER-Heat does not equal temperature. Define Heat - ANSWER-measures total kinetic energy of molecules in motion