where the time constant of the system is τ = C / ( h A ) {\displaystyle \tau =C/(hA)} . The heat capacitance C {\displaystyle C} may be written in terms of the object's specific heat capacity, c {\displaystyle c} (J/kg-K), and mass, m {\displaystyle m} (kg). The time constant is then τ = m c / ( h A ) {\displaystyle \tau =mc/(hA)} .