SECTION 1 of NEW UNIT C HEAT and TEMPERATURE.pdf

Needs and Wants Needs wants Standard of living Needs are the basic, required conditions that we must meet in order to live. It is necessary to our survival that we fulfill these needs Wants stem from needs and include ways in which needs could be met. The standard of living refers to the level o...

Needs and Wants Needs wants Standard of living Needs are the basic, required conditions that we must meet in order to live. It is necessary to our survival that we fulfill these needs Wants stem from needs and include ways in which needs could be met. The standard of living refers to the level of wealth, comfort, material goods, and necessities available to a particular society or individual. However, unlike needs, it is not vital to our survival that all of our wants be satisfied. It can be influenced by factors such as income, access to education and healthcare, employment opportunities, and overall economic conditions. 1.1 History of Heat Technology Heat Kinetic Energy thermal Energy Is the energy that transfers from a substance whose particles have a higher kinetic energy to a substance whose particles have a lower kinetic energy. Is the energy an object has as a result of its motion. Is the total kinetic energy of all particles in a substance. Example: - person walking - baseball in the air - item falling of a table Example: - warmth of the sun - heat from a heater - air in baking oven Early theories of heat 1.2 Million years ago early humans used fire for to cook their food and keep warm. Empedocles (450 BC) Empedocles’ believed that all matter was made up of earth, air, fire and water. He thought when objects burned, the fire inside was released. Caloric theory (1600s) The caloric theory is an obsolete scientific theory that heat consists of a self-repellent fluid called caloric, a massless fluid, that exited in all object and flows from hotter bodies to colder bodies. Caloric was also thought of as a weightless gas that could pass in and out of pores in solids and liquids. Benjamin thompson (Count Rumford) 1753 - 1814 In Germany, Count Rumford was in charge of building cannons. He discovered that when they bore the hole out of metal a great amount of heat was produced. It was at this time he theorized that heat was a form of energy resulting from friction. Julius mayer (1800s) In the 1800s, Julius Mayer was the first to discover the relationship between heat and energy. He was employed as a ship’s doctor on trips to the East Indies. He performed “bloodletting” on sick sailors, as it was believed this would cure them. He noticed that the blood of the sailors was darker red than that of the native populations in warmer climates. Julius mayer (1800s)..... Julius found that the sailors, being from northern colder climates, had less oxygen in their blood resulting in a darker red colour. The reason was this was that it had to work harder to keep the body warmer. Before Julius could write about his finding, the discovery between energy and heat was published by a famous scientist……… James Prescott Joule James prescott joule (1800s) He came up with the mechanical equivalent of heat, called the JOULE (J). Joule's apparatus for measuring the mechanical equivalent of heat. A descending weight attached to a string causes a paddle immersed in water to rotate and the "work" of the falling weight is converted into "heat" by agitating the water and raising its temperature. After further investigations and observations... Scientists decided that heat was not a substance, but a form of energy, that comes from the movement of tiny particles. Making sustainable choices sustainable Sustainable means that something can be maintained or continued. When we talk about sustainable use of resources, we mean that we are trying to use our resources wisely and do as little damage as possible to the environment when we use them.