A train with a blowing whistle that has a frequency of 550 Hz is travelling at a speed of 80.0 km/h toward a railway crossing where a car waits behind the barrier. If the
speed of sound is 345 m/s, what is the frequency of sound that reaches the car as
the train approaches the crossing? Do not leave any spaces in between the numeric
answer and the unit of measurement. Make sure that your answer has the
appropriate number of significant digits.

Astone is thrown into a pond. what happens to the amplitude of the resulting waves as they get farther from the point where the stone hit the water? explain.

Red light strikes a metal surface and electrons are ejected. if violet light is now used with a 10% greater intensity, what will happen to the ejection rate (number of ejected electrons per second) and the maximum energy of the electrons? a) greater ejection rate; same maximum energyb) same ejection rate; greater maximum energyc) greater ejection rate; greater maximum energyd) same ejection rate; same maximum energye) none of the above answers are correct

**urgent** roberto plans to use two transformers to reduce a voltage of 120 v to 4 v. he uses a transformer that has 300 coils in the primary winding and 50 coils in the secondary winding. he has four other transformers, as listed in the table. which transformer should roberto use to have an ending voltage of 4 v? a- w b-xc- yd- z