If a machine has an efficiency of 80% and it does 400 J of useful work, how much

₹0.0

Question: If a machine has an efficiency of 80% and it does 400 J of useful work, how much energy was supplied to the machine? (2023)

Options:

Correct Answer: 500 J

Exam Year: 2023

Solution:

Efficiency = Useful Work / Total Energy Input. Total Energy Input = Useful Work / Efficiency = 400 J / 0.8 = 500 J.

If a machine has an efficiency of 80% and it does 400 J of useful work, how much energy was supplied to the machine? (2023)

If a machine has an efficiency of 80% and it does 400 J of useful work, how much energy was supplied to the machine? (2023)

Step 1: Understand that efficiency is a measure of how much useful work a machine can do compared to the total energy it uses.
Step 2: Write down the formula for efficiency: Efficiency = Useful Work / Total Energy Input.
Step 3: Rearrange the formula to find Total Energy Input: Total Energy Input = Useful Work / Efficiency.
Step 4: Plug in the values: Useful Work is 400 J and Efficiency is 80%, which is 0.8 in decimal form.
Step 5: Calculate Total Energy Input: Total Energy Input = 400 J / 0.8.
Step 6: Perform the division: 400 J divided by 0.8 equals 500 J.
Step 7: Conclude that the total energy supplied to the machine is 500 J.

Efficiency – Efficiency is the ratio of useful work output to the total energy input, often expressed as a percentage.
Energy Calculation – Understanding how to manipulate the efficiency formula to find total energy input based on given useful work and efficiency.