Section 14.3 Mechanical Advantage And Efficiency | Answer Key Pdf

Every machine involves an interaction between the user and the device: Input Force ( Ficap F sub i

A worker uses a ramp that is 6.0 meters long to lift a heavy crate up to a truck bed that is 1.5 meters high. What is the ideal mechanical advantage (IMA) of the ramp? Identify the Variables: Input Distance ( dinputd sub input end-sub ) = 6.0 m (the distance the crate is pushed) Output Distance ( doutputd sub output end-sub ) = 1.5 m (the vertical height the crate is raised) Step-by-step Solution:

Explanation: A rough surface creates more friction between the object and the ramp. This friction opposes motion, requiring additional input force to overcome.

Keep these equations handy when solving Section 14.3 review questions: Every machine involves an interaction between the user

No machine is 100% efficient because some work is always lost to friction as heat. Efficiency compares the work output to the work input. Formula:

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

Many physical science textbooks include odd-numbered answers in the back of the book. Summary Table for Quick Reference Work Input Force (in) × Distance (in) Joules (J) Work Output Force (out) × Distance (out) Joules (J) AMA Output Force / Input Force None (Ratio) IMA Input Distance / Output Distance None (Ratio) Efficiency (Work Out / Work In) × 100 Percentage (%) Formula: In physics, efficiency measures how much of

Efficiency tells you how well a machine converts input work to output work.

Explanation: IMA represents the theoretical maximum that would occur without friction. Since friction always reduces performance, AMA is always less than IMA.

(1) 80 N, (2) 12, (3) 70%, (4) False – Friction always exists. Additional factors include driving habits

$W_in = 100\text J$, $W_out = 100\text J$. Efficiency $= 100%$.

The percentage of work input that becomes work output . Efficiency is always less than 100% because some work is always used to overcome friction . Formula:

Explanation: The textbook specifically identifies rolling resistance and air drag as major factors. Additional factors include driving habits, tire pressure, and mechanical condition.