Question

A block of copper (c = 390 J/kg°C) is heated from 20.0 C to 60.0 C. How much heat (in J) is absorbed by the copper if its mass is 45.0 g?

Answer 1

\[Q=mc(T_f-T_i)\]
Q = (0.045 kg)(390 J/kg°C)(60.0° C - 20°C)

Answer 2

I agree with @peachpi

Answer 3

just a slight quibble:
\[Q = (0.045\text{ kg})(390\frac{\text{ J}}{\text{kg }^\circ\text{C}})(60.0\ ^\circ\text{C} - 20.0\ ^\circ \text{C)}\]

Don't want to lose those significant figures or mangle the units!