We began class today by reviewing where we have been and where we are headed with class. We reviewed the powerful ideas we have learned so far:
Light rays leave a source in all directions
Light rays travel in straight lines
Light rays bounce off smooth objects like mirrors in a regular way (angle of incidence = angle of reflection)
Light rays bounce off rough objects in all directions
For someone to see an object, light rays must enter the eye
Light rays form the sides of similar triangles in pinhole cameras: H/D = h/d
Objects left for a long time in a room reach the same temperature, room temperature
Materials conduct heat and energy at different rates
Heat flows from a heat source to colder objects
Hot and cold water, when mixed together, come to a common temperature in between the hot temperature and the cold temperature; that is called the equilibrium temperature
Change in temperature will be smaller for a bigger amount of water
Change in temperature will be bigger for smaller amount of water
Conservation of energy: heat lost = heat gained
Heat energy lost by hot water: (mass of hot water)(T change of hot water)(c of water)
Heat energy gained by cold water: (mass of cold water)(T change of cold water)(c of water)
c is a property of materials called specific heat. Specific heat is the amount of heat energy needed to raise the temperature of one gram of the material by one degree Celsius.
Water is a standard: c = 1 calorie is needed to raise the temperature of 1 gram of water (at 1 atmosphere of air pressure) by 1 degree Celsius