Which of these would be best explained by the doppler effect? a) the change in frequency as you shorten a guitar string. b) the change in pitch heard as an ambulance approaches you. c) the change in volume as a train pulls away from the station. d) the change in speed of a sound wave as it travels from air into water

During a medieval siege of a castle, the attacking army uses a trebuchet to hurl heavy stones at the castle walls. if the trebuchet launches the stones with a velocity of at an angle of 50.0°, (a) how long does it take the stone to hit the ground? (b) what is the maximum distance that the trebuchet can be from the castle wall to be in range? (c) how high will the stones go? show all your work.