Question

Which of the following would require more energy to heat it from 10°C

to 20°C?
a. 200 kg of water
b. 200 kg of aluminum
c. 100 kg of steel

Answer 1

Explanation: A

`$$The heat $Q$ which a body absorbs or radiates can be expressed as:$$Q=m c \Delta T$$Where $m$ is the mass, $c$ is the specific heat capacity and $\Delta T$ is the change in temperature.`

`$$Substitute the known and given values into the equation above and calculate the results:`

`\begin{aligned}Q_(w) &=m_(w) c_(w) \Delta T=200 \cdot 1000 \cdot(20-10)=2 \cdot 10^(6) \mathrm{~J} \\Q_(A l) &=m_(A l) c_(A l) \Delta T=200 \cdot 897 \cdot(20-10)=1.8 \cdot 10^(6) \mathrm{~J} \\Q_(s) &=m_(s) c_(s) \Delta T=100 \cdot 420 \cdot(20-10)=4.2 \cdot 10^(5) \mathrm{~J}\end{aligned}`

`\text { Therefore, } 200 \mathrm{~kg} \text { of water would require the most energy to heat up. }`