Which type of wall would make the best soundproofing for a room?

A.) 1.0 cm thick glass

B.) two layers of 0.5 cm thick glass with 0.5 cm of air between them

C.) two layers of 0.5 cm thick glass with 0.3 cm of vacuum between them

D.) 1.0 cm thick steel

Acave rescue team lifts an injured spelunker directly upward and out of a sinkhole by means of a motor-driven cable. the lift is performed in three stages, each requiring a vertical distance of 11.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.80 m/s; (b) he is then lifted at the constant speed of 4.80 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 78.0 kg rescue by the force lifting him during each stage

Occurs when an energy source transfers heat directly to another subject space; an example would be an object becoming warm by sitting in the sunshine

It may seem strange that the selected velocity does not depend on either the mass or the charge of the particle. (for example, would the velocity of a neutral particle be selected by passage through this device? ) the explanation of this is that the mass and the charge control the resolution of the device--particles with the wrong velocity will be accelerated away from the straight line and will not pass through the exit slit. if the acceleration depends strongly on the velocity, then particles with just slightly wrong velocities will feel a substantial transverse acceleration and will not exit the selector. because the acc