An element in an instrumentation system outputs a frequency proportional to the input pressure and inversely proportional to the square root of temperature. For an increase in pressure of 200 Pa at a constant temperature of 300 K, the frequency increases by 150 Hz. When the pressure is 800 Pa and the temperature is 250 K, the frequency is 450 Hz. Determine the frequency when the pressure is 1000 Pa and the temperature is 280 K. Identify the system element and justify your answer.