A beam of spin-1/2 particles in the |+z) state enters a uniform magnetic field Bq in the x-z plane oriented at an angle theta with respect to the z axis. At time T later, the particles enter an SGy device. What is the probability the particles will be found with S_y - fi/2? Check your result by evaluating the special cases theta=0 and theta = pi/2.

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

not too sure thinking all accelerations are pointed down