A rock group is playing in a bar. Sound emerging from the door spreads uniformly in all directions. The intensity level of the music is 66.9 dB at a distance of 3.36 m from the door. At what distance is the music just barely audible to a person with a normal threshold of hearing

A26 cm object is 18 cm in front of a plane mirror. a ray of light strikes the object and is reflected off the mirror at a 42-degree angle. what is the angle of reflection? degrees what type of image is formed? what is the size of the image? cm

Air is contained in a variable-load piston-cylinder device equipped with a paddle wheel. initially, air is at 400 kpa and 17°c. the paddle wheel is now turned by an external electric motor until 75 kj/kg of work has been transferred to air. during this process, heat is transferred to maintain a constant air temperature while allowing the gas volume to triple. calculate the required amount of heat transfer in kj/kg.

Avector a⃗ has a length of 8.6 m and points in the negative x direction. find the x component of the vector −3.7a⃗ .