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"Hold on," Sam said. "That answer key is for a brand new, perfectly lubricated system. Look at this thing. It’s got rust on the gears and the chain is stiff. That answer key is showing us —what should happen. We need the AMA —what is happening."
Explanation: Reducing friction increases the actual mechanical advantage by allowing more input work to be converted into useful output work.
24%
This relationship can also be expressed in terms of mechanical advantage and ideal mechanical advantage:
Below are typical concept check questions and calculation problems found in typical physical science textbooks (such as Pearson/Prentice Hall Physical Science) for Section 14.3. Part 1: Conceptual True/False & Fill-in-the-Blank "Hold on," Sam said
FoutFinthe fraction with numerator cap F sub out end-sub and denominator cap F sub in end-sub end-fraction Percentage of useful work
Understanding how machines multiply force and transfer energy is a foundational concept in physics and engineering. In introductory physics and physical science curriculum, focuses on quantifying how well tools make work easier. It’s got rust on the gears and the chain is stiff
Section 14.3, usually titled "Mechanical Advantage and Efficiency," dives into the mechanics of simple machines (levers, pulleys, inclined planes). It answers two fundamental questions:
| Term | Definition | |------|-------------| | Mechanical Advantage | Force multiplier of a machine | | Ideal MA (IMA) | MA without friction (distance in / distance out) | | Actual MA (AMA) | MA with friction (F_out / F_in) | | Efficiency | (AMA / IMA) × 100% | 24% This relationship can also be expressed in
In physics, efficiency measures how much of the work put into a machine is converted into useful output work. Due to friction converting kinetic energy into thermal energy (heat), no real machine can ever be 100% efficient. The Efficiency Formula
