The ratio related to ideal mechanical advantage in a simple machine is called the

• A. Efficiency
• B. Actual mechanical advantage
• C. Power
• D. Ideal mechanical advantage

Answer: (D)

The main idea is how a simple machine would amplify your effort if there were no losses. In an ideal (frictionless) machine, energy is conserved, so input work equals output work: F_in times d_in equals F_out times d_out. From this, the ratio of output force to input force (the mechanical advantage) equals the ratio of input distance to output distance. That same ratio is defined as the ideal mechanical advantage. So IMA is the factor by which the machine would multiply your effort in the perfect case. In real machines, friction lowers the actual mechanical advantage, and efficiency relates the two as efficiency = MA/IMA.