An ambulance blowing a siren of 700 hz frequency traveling slowly towera vertical wall with a speed 2m/s . the speed of sound is 350 m/s . how many beats are heared by the driver per second?

And length l is over hanging from edge of a smooth horizontal table such that 3/4th of its length lying on table the work done in pulling the chain

Abody of mass 2 kg and density 8000 kg per metre cube is completely immersed in a liquid of density 800 kg per metre cube find the force of beyonce on it ​

Anew semiconductor has nc=10^19/cm^3,nv=5×10^18/cm^3 and eg=2ev. it is doped with 10^17 donors(fully ionized).calculate electron hole and intrinsic carrier conc. at 627°c? also sketch the simplified band diagram showing the position of ef.​