Physics

Problem

An immersion heater rated at

120\,\text{W}

is used to heat

0.50\,\text{kg}

of water from

20^{\circ}\text{C}

80^{\circ}\text{C}

. Assuming no energy losses to the surroundings and taking the specific heat capacity of water to be

4.18\times10^{3}\,\text{J}\,(\text{kg}\cdot^{\circ}\!\text{C})^{-1}

, for approximately how long must the heater operate? a)

8.7\,\text{min}

2.4\,\text{min}

17\,\text{min}

35\,\text{min}