Work Done = Applying of force or the movement of something by that specific force. Force x the time it is performed is called Impulse. Force x the distance is called work. Work = Force x Distance (W=Fd)
Joule = Resulting unit of work / newton=meter (N.M). Large Joules are kilojoules and mega joules.
How fast the work is done = Power. Power = Work Done / Time Interval. Unit of Power is the Joule per second, also known as the Watt. One kilowatt (kW) equals 1000 Watts.
The metric system of units used kilowatts to rate automobiles. 1 hp (horsepower), is the same as 0.75 kW. 134 hp is a 100 kW engine.
Potential Energy: Energy that is stored and held. Example: Chemical energy in fuels is potential energy.
Acting against earth's gravity requires work. Gravitational Potential Energy = Weight x Height/PE=mgh
Kinetic Energy: Energy of motion. Kinetic Energy depends on the mass and speed of an object.
Kinetic Energy = 1/2 Mass x Speed2 KE=1/2 mv2
Net Force x Distance = Kinetic Energy Fd=1/2mv2 Note: The speed is squared, speed of an object is doubled, kinetic energu is quadrupled. Work-Energy Theorem. Whenever work is done, energy changes. Work=Change in Energy.
Law of Conservation of Energy: Energy cannot be created or destroyed. It can be transformed from one form into another, but the total amount of energy never changes.
Machine: A device used to multiply forces or change the direction of the force. Example of a Machine: Lever. Work input will equal the work output.
Work Input=Work Output (force x distance) input = (force x distance) output.
Mechanical Advantage: Ratio of output to input force for a machine. Example: (80N)/(10N) or 8. Variation of the Lever: Pulley.
Example: Raise a load 1 m, it needs to be pulled up 2m. Mechanical Advantage is 2. Example: (500N)/(100N) or 5.
Efficiency: Ideal Machine is 100% efficiency. 100J of Work expected, 98J recieved, 2 J lost, 98% efficiency. Efficiency= Useful work output/total work input. Efficiency= Actual Mechanical Advantage/Theoretical Mechanical Advantage. Converting efficiency into percent. Efficiency 0.25, expressed as 25%. Can be figured out using 0.25 x 100%.
Mechanical Advantage Example: Input Distance/Output Distance = 10m/1m = 10.
Energy for Life: Photosynthesis. Energy input is needed.