Atrain station bell gives off a fundamental tone of 500 hz as the train approaches the station at a speed of 20 m/s. if the speed of sound in air is 335 m/s, what will be the apparent frequency of the bell to an observer riding the train?
a. 532 hz
b. 530 hz
c. 470 hz
d. 472 hz

On a horizontal frictionless surface, a small block with mass 0.200 kg has a collision with a block of mass 0.400 kg. immediately after the collision, the 0.200 kg block is moving at 12.0 m/s in the direction 30° north of east and the 0.400 kg block is moving at 11.2 m/s in the direction 53.1° south of east. use coordinates where the +x-axis is east and the +y-axis is north.(a) what is the total kinetic energy of the two blocks after the collision (in ) what is the x-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your ) what is the y-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your answer.)