In which example does speed remain constant while velocity changes?
OA) A boy skates east at 3 m/s.
OB) A biker goes around a circular track at 5 m/s.
OC) An ant crawls northwest toward a crumb at 2 cm/s.
OD) A swimmer swims in a lane toward the shallow end at 4 m/s.

sonar - device which is used to find the submit submarines, sankalp ship. sonar waves consists of a transmitter and detector which are installed in the observation centre on board of a ship. the ultrasonic waves are sent into the sea at high frequency about 1000 khz in all direction.

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