Arevolving searchlight on an island 6 miles from shore turns at the rate of 2 revolutions per minute in the clockwise direction. at what speed is the light beam travelling along the straight shoreline the instant it makes an angle of 45◦ with the shoreline? (recall: one revolution = 2π radians.)

 Revolving velocity = 2 km/s

Explanation:

Velocity of circular motion = Radius x Angular velocity.

Angular velocity, ω = 2πf, where f is the frequency of circular motion.

Here frequency, f = 2 revolutions per minute

                     f = revolutions per second.  

Angular velocity, ω = 2πf = 0.209 radians/second.

Radius = 6 miles = 6 x 1.6 x 10³ = 9.6 x 10³ m.

Linear velocity =  9.6 x 10³ x 0.209 = 2006.4 m/s= 2 km/s

Revolving velocity = 2 km/s

photocells convert light energy to electricity

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