Physics for Future Presidents Notes-Final Exam

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Energy: the ability to do work. Work= force x displacement. Power=energy/time Power is measured in watts or horsepower. Joules/sec=watts 1hp=746w=1kw Basal metabolic rate 2000kcal/day= 100w
Batteries store energy in chemical form. They release energy by pumping electrons’ through wires from the minus pole to the plus pole. Devices inbetween convert this energy to another form, Efficieny- e.motor=85%, combustion= 20% Hydrogen is not a source of energy but a means of transportation Types of energy: kinetic e(in joules)= .5mv^2. Solar energy- 1gw per km^2 Solar energy can be turned into electricity through solar cells 15%=cheap, 40% efficiency=expensive. Caloric theory of heat=caloric fluid flows from hot object to cold. Heat engine= device to turn heat energy into useful work: heat comes from something hot but only some goes to useful work. Satellites=free fall. Ionizing radiation=energy in the form of waves or paricle Beta radiation-just an electron, wont go through skin but really bad inside you alpha- he2+ nucleus-wont go through skin but bad once inside. Comes from radioactive particles like lead 210 or iodine. gamma- high energy photon, may go through you. neutrineos-noninteracting, come from fusion, cosmic rays-very powerful. Come from supernovas. Moves at speed of light moderator-slows neutrons b/c they are absorbed better when slow ciritical mass needed for nuclear bomb-5kg, resistence of wire depends on length, longer=more resistance. Thickness-thinner=bigger resistance, material. Escape velocity=velocity required on the surface to completely leave a planet Rcket-goes nowhere near escape velocity – drag from atmosphere is bad, goes slower but carries fuel Tin Celsius = Tin Fahrenheit − 32 × 5 9 Tin Fahrenheit = Tin Celsius × 9 + 32 . 5 Nuclear energy

Source of energy of energy in plants=radioactive particles such as uranium and plutonium. A chain reaction is the doubling law that takes you from small numbers to high numbers in a small number of...
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