All Exams Test series for 1 year @ ₹349 only
Question

If a machine has an efficiency of 80%, it means:

This question was previously asked in
RRB NTPC 2024 Undergraduate CBT 1 Question Paper (29-Aug-2025) (Shift 1)
The correct answer is
the machine loses 20% of the input

The correct answer is 3. the machine loses 20% of the input.

Efficiency is defined as the ratio of useful output work to the total input work. It's expressed as a percentage.

If a machine has an efficiency of 80%, this means that 80% of the input energy is converted into useful output work. The remaining 20% is lost due to factors like friction, heat, and sound.

Let's examine why the other options are incorrect:

  • Option 1: Velocity ratio and mechanical advantage are related to the machine's capabilities but don't directly define its efficiency. Efficiency focuses on energy conversion.
  • Option 2: An 80% efficient machine *does* have losses in input energy; that's what the 20% represents.
  • Option 4: A machine can never produce more output energy than the input energy due to the law of conservation of energy. This would imply a greater than 100% efficiency, which is impossible.

Therefore, an 80% efficiency indicates a 20% energy loss during the work process.

Was this answer helpful?

Similar Questions

  1. Find the efficiency of a pulley system which has a mechanical advantage of 2.5 and where the load lifts by 2.5 meters on pulling the rope by 10 m.

  2. The effort applied to move a load is 15 units and the mechanical advantage is observed to be 3. Find the load.

  3. An effort of 5 units is applied on a 10-unit load. The distance travelled by the effort and the load are 50 and 20 units, respectively. Find the efficiency of this machine.
  4. The force applied to overcome a load is called _____.
  5. In practice, the work output of a machine is _____ the work input due to the effect of friction.
  6. The efficiency of a machine can never be _____.
  7. An effort of 5 units is applied on a 10-unit load. The distance travelled by the effort and the load are 50 and 20 units, respectively. Find the efficiency of this machine.
  8. The velocity ratio of a simple machine is the ratio of distance traveled by the ________ to the distance traveled by the ________ in the machine. 


Important Questions from Mechanical Advantage

  1. Find the efficiency of a pulley system which has a mechanical advantage of 2.5 and where the load lifts by 2.5 meters on pulling the rope by 10 m.

  2. The effort applied to move a load is 15 units and the mechanical advantage is observed to be 3. Find the load.

  3. An effort of 5 units is applied on a 10-unit load. The distance travelled by the effort and the load are 50 and 20 units, respectively. Find the efficiency of this machine.
  4. The force applied to overcome a load is called _____.
  5. In practice, the work output of a machine is _____ the work input due to the effect of friction.
Need Expert Advice?
Upcoming Exams
RRB Technician
October 06, 2026
RRB JE
October 27, 2026
RRB ALP
November 03, 2026
Test Series
RRB ALP img
Railways
RRB ALP 2026 Mock Test series
1035 Tests 1 Tests Free
1088 Attempts
4.3(239)
English, Hindi

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App