Sound with frequency 1200 HzHz leaves a room through a doorway with a width of 1.03 mm . At what minimum angle relative to the centerline perpendicular to the doorway will someone outside the room hear no sound

Explanation:

The problem is based on diffraction of sound . In this phenomenon sound does not travel in straight line . It turns around the pointed corner . Due to it,  sound intensity forms fringes ie intensity are not uniformly scattered on all around.

wave length λ = velocity / frequency

= 340 / 1200

λ  = 0.2833 m .

slit width  a = 1.03 x 10⁻³

angular width of central fringe = 2 λ / a

= 2 x .2833 / 1.03 x 10⁻³

= .5666 x 10³ radian .

566.6 radian .

Within this angle intensity of sound is maximum.

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.

magnets not strong enough

explanation: