Ideas of normal and abnormal are largely shaped by social standards and can have profound social ramifications. Learning Objective. Analyze the challenges inherent in trying to define normal and abnormal. What is considered normal changes with changing societal standards. Despite the challenges inherent in defining normal, it is still important to establish guidelines so as to be able to identify and help people who are suffering. This is the goal of the Diagnostic and Statistical Manual of Mental Disorders (known as the DSM-5), a publication in the field of clinical psychology.
Launching a water rocket. The rocket is in its peak with no water inside it. Water and gas are used in combination, with the gas providing a means to store energy, as it is compressible, and the water increasing the propellant mass fraction and providing greater force when ejected from the rocket's nozzle.
Occasionally a separate propellant is used to operate the gas generator which supplies the gas to drive the turbopumps of liquid rockets. In the V-2, for example, hydrogen peroxide was decomposed to supply the hot gas for the main turbopumps, although the main rocket propellants were alcohol and liquid oxygen.