Question

If a machine is lubricated with oil.

• A. The mechanical advantage of the machine increases
• B. Both its mechanical advantage and also mechanical efficiency increases
• C. Mechanical efficiency of machine increases
• D. Its efficiency increases but its mechanical advantage decreases

Answer 1

Answer: (C)

Mechanical efficiency of machine increases

Solution: As, mechanical efficiency of a machine is defined as the ratio of the output work to the input energy, so when the machine is lubricated with oil the force of friction becomes less and output given by the machine increases. Therefore mechanical efficiency of the machine also increases.

Hence, the correct option is (C).