A police car is heading towards you with its siren blaring. Explain what is happening to the

wavelength as the police car is moving towards you and what is happening to the wavelength

when the police car moves away from you.

make sure to use evidence and explain your answer.

how to make a simple air condition

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.