As part of a NASA experiment, golfer Tiger Woods drives a golf ball on the moon, where g = 1.60 m/s2. He launches a golf ball with a speed of 285 km/h, at an angle of 42° with the horizontal. What horizontal distance will his drive travel before landing back on the surface of the moon. Ignore the curvature of the moon.​

Horizontal distance, R = vo2 sin(2x45)/g

v = 285 km/h = 79.17 m/s

R = 79.172 x 1/1.6

R = 3917 m

R = 3.9 km

a and b sometimes have a positive value

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