A precision laboratory calibration bath filled with a synthetic silicone fluid is switched on to heat the fluid.
The figure below shows how the temperature of the silicone fluid changed over time from the moment the bath was switched on.
When the calibration bath was switched on, the temperature of the silicone fluid did not immediately start to increase.
Suggest one reason why.
The energy transferred to the silicone fluid in the first 300 s was 125 000 J125\,000\text{ J}125000 J.
Given that the specific heat capacity of the silicone fluid is 1600 J/kg ∘C1600\text{ J/kg }^\circ\text{C}1600 J/kg ∘C.
Determine the mass of the fluid inside the calibration bath. Use the graph above.
Give your answer to 2 significant figures.
The straight-line section of the curve in the graph can be used to calculate the useful power output of the calibration bath heater.
Explain how.