Why is the work output of any real machine less than the work needed to operate it

An example of forced convection is the movement of hot air by a fan (t or f)

I need to make a box that would keep foods hot, but can only use 1 out of the following 4 materials; rubber, glass, aluminum foil, and stainless steel. Which material would be best to use to make the box?

What beat frequencies result if a piano hammer hits three strings that emit frequencies of 392.0, 587.3, and 146.8 hz? (enter your answers from smallest to largest.) ?

Which does not provide a significant voltage difference in a circuit? A) wet cells B) wires C) electrical outlet D) dry cells

A teacher sends her students on a treasure hunt. She gives the following instructions: 1. Walk 300 m north 2. Walk 400 m northwest 3. Walk 700 m east-southeast and the treasure is buried there.

A long distance runner has an average speed of 4m/s during a race. How far does the runner travel in 20 minutes?

Density is calculated by dividing

The one island species evolved into three different species. This is called?

Find the components of vector M shown in figure 5-7

Electrical current is actually made of a. static charges. b. moving electrons. c. high or low voltage. d. resistance within a circuit.