In this lesson our instructor talks about power and simple machines. He discusses alternate formulas, units, and the block and tackle systems. He lectures on machine, levers, and ramps. Four complete example problems round up this lesson.
Power is a measure of how quickly we put work into a system. Mathematically,
Since work is a transfer of energy (W=∆E), we can also formulate power as
Finally, we can also formulate it as
[Note: this requires you to use the dot product for vectors. If you aren't familiar with dot products, this is equivalent: P = |→F| |→v| cosθ.]
Power has the unit of joule per second ([J/S]). We call this a watt (W).
Simple machines are based on the idea of conservation of energy. Instead of using a large force over a small distance, we can use a small force over a large distance and still put in an equivalent amount of work.
Power & Simple Machines
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
This book includes a set of features such as Analyzing-Multiple-Concept Problems, Check Your Understanding, Concepts & Calculations, and Concepts at a Glance. This helps the reader to first identify the physics concepts, then associate the appropriate mathematical equations, and finally to work out an algebraic solution.