"So the machine is half as good as the book says?" Leo asked.
= Input force (force applied to the machine, measured in Newtons) Foutputcap F sub output end-sub
This is the percentage of work input that successfully becomes work output. Because friction is always present, efficiency is always less than 100% .
A:
Force is measured in Newtons (N), distance in meters (m), and work in Joules (J). Mechanical advantage is always a bare number with no units because the units cancel out. "So the machine is half as good as the book says
A mechanic uses a pulley system to lift an engine out of a car. The engine weighs 2,400 N. The mechanic pulls with a force of 600 N. What is the Actual Mechanical Advantage of the pulley system?
If you need additional help or want to check more problems, consider these resources:
Comprehensive Guide to Section 14.3 Mechanical Advantage and Efficiency
Keep these equations handy when solving Section 14.3 review questions: A: Force is measured in Newtons (N), distance
The fluorescent lights of Room 302 hummed with the same tension that filled the air. It was 3:45 PM on a Friday, and Mr. Henderson’s Physics class was supposed to be gone. Instead, four students remained, staring at a daunting pile of gears, pulleys, and a conspicuously empty grade book.
Efficiency=(Work OutputWork Input)×100Efficiency equals open paren the fraction with numerator Work Output and denominator Work Input end-fraction close paren cross 100
To find how a machine alters force or distance, use these two distinct equations:
Publishers like McGraw-Hill, Pearson, or Holt often have password-protected sites, but some answer keys can be found through authorized educational sources. The engine weighs 2,400 N
Copying answers without understanding the formulas will not help you on the upcoming quiz. Use the key to learn from your mistakes!
Actual Mechanical Advantage (AMA)=Output Force (Fout)Input Force (Fin)Actual Mechanical Advantage (AMA) equals the fraction with numerator Output Force open paren cap F sub out end-sub close paren and denominator Input Force open paren cap F sub in end-sub close paren end-fraction
| Problem | Step-by-Step Solution | | :--- | :--- | | A lever is used to lift a 600 N rock with an effort of 200 N. The load is 0.2 m from the fulcrum, and the effort is applied 0.8 m from the fulcrum. | a) Actual Mechanical Advantage (AMA): $$AMA = \frac\textLoad\textEffort = \frac600 \text N200 \text N = 3$$ b) Velocity Ratio (VR) / IMA: $$VR = \frac\textEffort Distance\textLoad Distance = \frac0.8 \text m0.2 \text m = 4$$ c) Efficiency: $$η = \fracMAVR \times 100% = \frac34 \times 100% = 75%$$ | | 2. Ramp: A ramp is 4.0 m long and 1.0 m high. A 100 N box is pushed up with 40 N of force. | a) Ideal Mechanical Advantage (IMA): $$IMA = \frac\textLength (Input)\textHeight (Output) = \frac4.0 \text m1.0 \text m = 4.0$$ b) Actual Mechanical Advantage (AMA): $$AMA = \frac\textLoad\textEffort = \frac100 \text N40 \text N = 2.5$$ c) Efficiency: $$η = \fracAMAIMA \times 100% = \frac2.54.0 \times 100% = 63%$$ | | 3. Efficiency: A machine has a work output of 120 J and an efficiency of 24%. | a) Find Work Input: $$\textWork Input = \frac\textWork OutputEfficiency = \frac120 \text J0.24 = 500 \text J$$ b) Find Work Lost: $$\textWork Lost = \textWork Input - \textWork Output = 500 \text J - 120 \text J = 380 \text J$$ |
$\textEfficiency = \frac0.50.25 \times 100 = \mathbf200%$ ???
Before solving problems, it is crucial to understand the definitions of mechanical advantage (MA) and efficiency.