Question

Machines require proper maintenance for :

• A. their efficient use
• B. preserving them
• C. making them look good
• D. both (A) and (B)

Answer 1

The correct option is D

both (A) and (B)

1. A machine is a device that helps us to lift heavy loads, speed up the motion, or change the direction of the force in the desired direction.
2. The ratio between the output energy of the machine to the input energy is called the efficiency of the machine.

$Efficiency=\frac{Outputenergy}{Inputenergy}=\frac{Workdonebymachine}{workdoneonmachine}$.

3. The ratio between the useful load(resistance overcome) moved by the machine and the effort applied to do so is called mechanical advantage.

4. If $L$is the useful load moved by an effort $E$then the mechanical advantage

$M.A.=\frac{L}{E}$.

5. Mechanical advantage, as well as efficiency of the machine, has no units. It is a pure number. The reason for this is that both are ratios that have the same units. These units cancel with one another.

6. Machines required proper maintenance for their efficient use and for preserving them.

Hence, the correct option is an option (D).