Thermal energy Q
Q > 0: received by the body; Q < 0: released.
Thermal engineering · Thermodynamics
Sensible heat calculator
Calculate Q = mcΔT to heat or cool a mass without a phase change. Enter specific heat and initial and final temperatures to find signed thermal energy.
Created v1.0
By Thibaut Grzelak, Mechanical Analysis Engineer
02
Results
Temperature change ΔT
Δ°C
Final minus initial temperature.
Relation and numerical substitution
Q = mc(T_f − T_i)—
One body, constant c over the interval, no phase change or losses; no mixing of bodies.
01Formulas and symbols
Formulas used
ΔT
ΔT = T_f − T_iTemperature interval: a change of 1 K equals a change of 1 °C.Q
Q = m × c × ΔTm: mass; c: specific heat; Q: transferred energy.02Assumptions and limits
Scope of validity
- One body, constant c over the interval, no phase change or losses; no mixing of bodies.
03Validation example
Reference numerical case
- m = 2 kg, entered c = 4186 J/(kg·K), T_i = 20 °C and T_f = 30 °C: ΔT = 10 K; Q = 2 × 4186 × 10 = 83720 J = 83.72 kJ (≈ 84 kJ).
04References
Technical references
FAQ
Why is Q negative?
The final temperature is lower: the body releases energy. The sign does not mean a negative mass.
Can I use Fahrenheit?
Yes. Both temperatures are converted to kelvins before subtraction: an 18 °F interval equals 10 K.
Can this calculate melting ice?
No. A phase change also requires latent heat; mcΔT describes only a segment without a transition.
05Choosing specific heat
4186 J/(kg·K) is an entered example, not a universal constant. Select c for the material, phase and interval; for gases, specify constant-pressure or constant-volume conditions.
06Interpreting the energy
Q is ideal thermal energy for the body. Appliance consumption also depends on efficiency, losses and other heated parts. Heating time requires power.
07Interval versus absolute temperature
Celsius offsets cancel in T_f − T_i; the Fahrenheit scale factor remains. Do not multiply mc by final temperature alone.