Lucy needs to lift a crate to a shelf 20 m high. she does 12,000 j of work on a machine to her. the machine exerts a force of 500 n to lift the crate.
what is the efficiency of the machine?
4.2%
24%
58%
83%

When an object falls through the air and encounters air resistance its overall speed will be than if it had not encountered air resistance? (one word answer)

What are the primary responsibilities of a chemical engineer involved in "r& d"? develop large scale manufacturing operations discover new products and processes training of new chemists determine products needed by consumers

Three cards with holes are arranged in a straight line. a light is shined through the first card’s hole and travels through all three cards. what does this tell you about light rays? a) that light is reflected b) that light is refractive c) that light travels in a straight line d) that light does not travel in a straight line