Beijing 2013 Physics Examination Paper Multiple Choice Question 9 9.The specific heat of known water is 4.2x10^3J/kg.°C is released), then the mass is 2kg of water, and the temperature is determined by

Beijing 2013 Secondary School Entrance Examination Physics Exam Multiple Choice Question 9

9. It is known that the specific heat of water is 4.2x10^3J/kg.°C is released), then the mass of water is 2kg, and the temperature is reduced from 25 degrees to 20 °C. The heat released is ( )

A.4.2x104J

B.2.1x105J

C、1.68X105J

D.3.78x105J

Answer: A

Answers & Analysis:

Q=cm(t2-t1)=4.2x10^3J/kg.°Cx2kgx5°C=4.2x10^4J