14000kg of copper is heated using a heater with an effect of 1200W. The starting temperature is 20 degrees kelvin. After 8 minutes, the temperature is 120 degrees kelvin.

What is the heat capacity of copper in J/(kg K)?

What I get is:

(1200 * 60 * 8) / (14000 * (120-20)) = 0.411

The answer *should* be 430 J/(kg K). Can anyone tell me what I should be doing? :)

Question

14000kg of copper is heated using a heater with an effect of 1200W. The starting temperature is 20 degrees kelvin. After 8 minutes, the temperature is 120 degrees kelvin. 

What is the heat capacity of copper in J/(kg K)?

What I get is:

(1200 * 60 * 8) / (14000 * (120-20)) = 0.411

The answer *should* be 430 J/(kg K). Can anyone tell me what I should be doing? :)