A lever has a 2-meter effort arm and a 0.5-meter load arm. What is its ideal mechanical advantage?
A0.25
B2.5
C4
D1
IMA = effort arm / load arm = 2 / 0.5 = 4. The lever multiplies the input force by 4, but you must push 4 times the distance the load moves.
Question 2 Short Answer
A ramp requires 200 N of force to push a 500 N box to a height of 1 meter. The ramp is 3 meters long. What is the actual mechanical advantage?
Think about your answer, then reveal below.
Model answer: AMA = output force / input force = 500 / 200 = 2.5. The IMA = ramp length / height = 3 / 1 = 3. Efficiency = AMA / IMA = 2.5 / 3 = 83.3%. The difference between 3 and 2.5 is due to friction.
The IMA based on geometry predicts a force of 500/3 = 167 N, but friction increases the actual required force to 200 N. The efficiency of 83.3% means 16.7% of the input energy is lost to friction as heat.
Question 3 True / False
A machine with a mechanical advantage of 10 requires you to move the input 10 times the distance the output moves.
TTrue
FFalse
Answer: True
Conservation of energy requires that input work equals output work (in an ideal machine). If force is multiplied by 10, distance must be divided by 10. You push with less force but over a much greater distance.