Calculation of heat input

Calculate the change in internal energy (heat flux) of three bodies of different materials in heat transfer when the temperature of these bodies changes by $40$ degrees.

The amount of heat $Q$ that must be given to a substance to raise its temperature by a certain number of degrees depends on the specific heat $c$ of the substance, the mass of the substance $m$ and the desired temperature change $Δ t = t_{2}^{\circ} - t_{1}^{\circ}$ :

Q = c m Δ t^{\circ} = c m (t_{2}^{\circ} - t_{1}^{\circ})

Thus, in the heat exchange, the temperature of the substance will either rise or fall. If the temperature does not change, there is no heat exchange.

How to do it

Pick out some bodies from the test kit or classroom. Identify what your body is made of and weigh it. Find the specific heat of the substance in the test apparatus from the table below, searching the internet for more information if necessary. Record the data in the table.

Calculate yourself or let the calculator on the worksheet do the calculation. Answer the questions.

Calculator: amount of heat during heating and cooling of bodies

The calculator calculates the amount of heat required to heat bodies from a substance or the amount of heat released when they cool down, using the formula $Q = c m Δ t^{\circ} = c m (t_{2}^{\circ} - t_{1}^{\circ})$ . When using the calculator, enter the data in the table. The answer appears in the last row of the table.

Specific heat $c$ of matter	$\frac{J}{^{\circ} C \cdot k g}$
Mass $m$	$k g$
Initial temperature $t_{1}^{\circ}$	$^{\circ} C$
Final temperature $t_{2}^{\circ}$	$^{\circ} C$
Temperature change $Δ t$	$^{\circ} C$
Internal energy change $Q = c m Δ t^{\circ} = c m (t_{2}^{\circ} - t_{1}^{\circ})$	$J$ *

* A negative result indicates that the internal energy of the body decreased. A positive result indicates that the internal energy of the body increased.

The table shows the specific heats of several well-known substances.

Three bodies and the amount of heat required to heat them by $40$ degrees.

The body	$Q$ ( $J$ )
Aluminum test piece	$J$
	$J$
	$J$

Heating and cooling of bodies

Specific heats of some substances