Phase Change
Time (min) Temperature (oC)
0 15
1 32
2 45
3 48
4 54
5 54
6 54
7 54
8 54
9 59
10 60

A certain substance is a solid at 15°C. Sarah heated a sample of the solid substance in a beaker using a Bunsen burner during science class. She and her partner recorded the temperature at one-minute intervals. Their data is recorded in the table below. Based on the girls' data, when was the kinetic energy of the substance the greatest?

Arefrigerator uses r-134a as the working fluid and operates on the ideal vapor-compression refrigeration cycle except for the compression process. the refrigerant enters the evaporator at 120 kpa with a quality of 34 percent and leaves the compressor at 70°c. if the compressor consumes 450 w of power, determine (a) the mass flow rate of the refrigerant, (b) the condenser pressure, and (c) the cop of the refrigerator. (0.00644 kg/s, 800 kpa, 2.03)