Atruck moving at 36 m/s passes a police car moving at 45 m/s in the opposite direction. if the frequency of the siren is 500 hz relative to the police car, what is the change in frequency (in hz) heard by an observer in the truck as the two vehicles pass each other? (the speed of sound in air is 343 m/s.)

What is the magnitude of the resultant vector round your answer to the nearest tenth

If angle "a" is 25°, angle "b" is: a) equal to angle c b) less than angle c c) greater than angle c

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.