Why is friction between moving parts of machines undesirable?

What is The common value for the speed of light in a vacuum

During what phase of the cell cycle does cell division occur?

Calculate the power of a 120V drill that uses 15A of electricity.

A note is being played on a string on a guitar. The string is then pushed to the side while still in contact with the same fret. What happens to the frequency of the note then played compared to the original note?

Which change decreases the resistance of a piece of copper wire

As a skydiver falls, the air is forced to move around him. What energy transformation does this cause? A. Potential energy from the skydiver becomes potential energy in the atmosphere. B.

On your way to the dance through there is some slow driving person in front of you so you slam on the gas going 30 mi/hr to 60 mi/he. Luckily your date brought a stop watch and told you the whole thing took place in 10s.

The sources of the heat inside Earth

A microwave is rated at 750 watts. How long will it take the microwave to do 5700 J of work on a cup of water? Assume 100% efficiency. A) 0.13s B) 2s C) 7.6s D) 4,275,000 s

A block hangs at rest from the ceiling by a piece of rope. Consider the forces acting on the block. Is gravity present or absent?