Apowerboat is operating at night. from which direction(s) must the white masthead light be visible

Answer;

-The white light shines forward and to both sides (225 Degrees) and is required on all power-driven vessels. A masthead light must be displayed by all vessels when under engine power. The absence of this light indicates a sailboat under sail.

Explanation;

-Masthead light; Means a white light placed over the fore and aft center-line of the vessel showing an unbroken light over an arc of the horizon of 225 degrees and so fixed to show the light from right ahead to 22.5 degrees abaft of the beam on either side of the vessel, except that on a vessel of less than 12 meters (39'4") in length the masthead light shall be placed as nearly as practical to the fore and aft center-line of the vessel.

gas and liquid

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me