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%

The slotted link is pinned at o, and as a result of rotation it drives the peg p along the horizontal guide. compute the magnitude of the velocity and acceleration of p along the horizontal guide. compute the magnitudes of the velocity and acceleration of p as a function of θ if θ=(3t) rad, where t is measured in seconds.

Apackage of supplies is dropped from a plane, and one second later a second package is dropped. neglecting air resistance, the relative velocity of the 1st package viewed from the second will 56) a) increase. b) be constant. c) be zero. d) depend upon their weight. e) decrease

The sun generates both mechanical and electromagnetic waves. which statement about those wave is true?