3) A spherical source radiates sound uniformly in all directions. At a distance of 20 m, the sound intensity level is 100 dB with 0 dB corresponding to 10-12 W/m2. a) At what distance from the source is the intensity level 40 dB. b) What power is radiated by this source

think its the third option

real, smaller and upside-down.   so the answer should be b.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

k2s for potassium sulphide