Concept:Friction in a machine reduces its efficiency and mechanical advantage.
Explanation:Efficiency is the ratio of useful work output to work input.
Friction increases the work input needed for the same output, so efficiency decreases.
Velocity ratio depends only on the machine’s geometry, not on friction.
Mechanical advantage is reduced by friction because more effort is needed to overcome it.
Therefore, the correct statement is that efficiency decreases with an increase in friction.
Answer:B. Efficiency decreases with an increase in friction