B. Find the average frequency of a police car siren if at rest is has a frequency of 1800 Hz but has a frequency of 2000 Hz as it moves towards you.​

Refrigerant-134a flows through a carnot heat pump cycle at 0.5 kg/s. it is known that the maximum absolute temperature in the cycle is 1.1 times the minimum absolute temperature, and the net power input to the cycle is 2.5 kw. if the refrigerant changes from a saturated vapor to a saturated liquid during the heat rejection process, determine the maximum magnitude of the enthalpy of vaporization for this process in kj/kg (with 3 significant figures).

In which item is energy stored in the form of gravitational potential energy? a. a slice of bread b. a compressed spring c. an apple on a tree d. a stretched bow string

Which if the following types of research is conducted on multiple occasions over time