An ambulance driving with velocity v/8 where v is the speed of sound, emits a siren with a frequency of . what is the frequency heard by a stationary observer toward whom the ambulance is driving?

A10nc charge sits at a point in space where the magnitude of the electric field is 1500 n/c. what will the magnitude of the field be if the 10 nc charge is replaced by a 20 nc charge? assume the system is big enough to consider the charges as small test charges.