The amount of heat Q needed to increase the temperature of a substance by [tex]\Delta T[/tex] is given by
[tex]Q=m C_s \Delta T[/tex]
where
m is the mass of the substance
[tex]C_s[/tex] is the specific heat capacity of the substance
[tex]\Delta T[/tex] is the increase of temperature
For iron, the specific heat capacity is [tex]C_s = 0.45 J/g ^{\circ}C[/tex]. The amount of heat supplied to this sample is Q=895 J and the temperature increases by [tex]\Delta T = 55.0 ^{\circ} C[/tex], so we can re-arrange the previous formula to find the mass of the sample:
[tex]m= \frac{Q}{C_s \Delta T}= \frac{895 J}{(0.45 J/g^{\circ}C)(55.0^{\circ}C)}=36.2 g [/tex]
