Physics Final Exam Questions and Answers 2024

What are the temperatures for freezing water on the Celsius and Fahrenheit scales? For boiling water - Freezing: 0 °C and 32 °F Boiling: 100 °C and 212 °F Is the temperature of an object a measure of the total kinetic energy of molecules in the object or a measure of the average kinetic energy per molecule in the object? - Temperature is a measure of the average kinetic energy per molecule in the object. Internal energy or Thermal energy is a measure of the total kinetic energy of the molecules of the object. The Internal/Thermal energy is directly related to the temperature of the substance. If an object is at a higher temperature is has more internal energy than an object at a lower temperature. What is meant by the statement "a thermometer measures its own temperature"? - A thermometer when placed in contact with an object at a given temperature reaches thermal equilibrium with object and thus the thermometer is measuring both the temperature of the object and its own temperature. What are the temperatures for freezing water and boiling water on the Kelvin temperature scale? - The Kelvin scale is directly proportional to the Celsius scale but shifted by 273 K, thus the freezing point of water in Kelvin is 273 K and the boiling point is 373 K. How much energy can be taken from a system at 0 K? - When a system is at 0 K no more energy can be taken. This is absolute zero and implies that all the molecules are completely at rest (no kinetic energy) and no more energy can be taken. The temperature can not drop below 0 K. When you touch a cold surface, does the cold travel from the surface to your hand or does energy travel from your hand to the cold surface? Explain. - Heat (energy transfer) always occurs naturally from the higher temperature object (in this case the hand) to the lower temperature object (cold surface). Distinguish between temperature and heat - Temperature is related to how hot or cold something is and more specifically the average kinetic energy of the molecules. Heat is a measure of energy transfer. When energy is transferred to or from an object its temperature can change. Distinguish between heat and thermal energy - An object can contain thermal/internal energy due to its temperature. When an object has thermal energy it has the ability to give away or take on more thermal energy. Heat is the process of energy transfer. When an object loses "heat" it is actually losing internal energy and the process of transferring the energy is heat. Heat is energy in transit (movement) while internal energy is something that a substance has. What determines the direction of heat flow? - In natural situation, heat flows (energy flows) from the higher temperature object to the lower temperature object. The only way the reverse is possible is if it is forced to move in the opposite direction. Distinguish between a calorie and a Calorie. - 1 Calorie = 1000 calories (Calories are food Calories). Distinguish between a calorie and a joule. - 1 calorie = 4,186 Joules Which warms up faster when heat is applied- iron or silver? - In order to answer this question, we must know the specific heat capacity of iron and silver. Material Specific heat Capacity [J/(kg °C)] Iron 448 Silver 234 When equal amounts of heat are added to the same amount of iron and silver, the silver will change temperature by a greater amount (or quicker if you think about putting both items over a flame) since it has a lower specific heat capacity. The lower the specific heat capacity, the easier it is to change the temperature of the substance. Does a substance that heats up quickly have a high or low specific heat capacity? - A substance that heats up quickly has a low specific heat capacity.