Question

Which of the following statements is true?

1)Efficiency is calculated by multiplying work input and work output.
2)a few machines are 100 percent efficient.
3) Some machines are frictionless.
4)The ratio of work output to work input is always less than one.

Answer 1

4)

Step-by-step explanation:

Efficiency is calculated by dividing the energy out by energy in, not multiplying

No machines are 100% Efficient

No machines are frictionless

4) is true