WAEC Physics 2018 Paper

Concept:Newton's law of cooling gives the rate of heat loss from a body in terms of its temperature, the surroundings, and the nature of its surface.Explanation:Total heat energy lost per second is:$$\frac{Q}{t} \propto A(T - T_0)$$Here, $A$ is the exposed area, $T$ is the temperature of the body, and $T_0$ is the temperature of the enclosure.To find heat energy lost per unit area, divide by $A$:$$\frac{Q}{At} \propto (T - T_0)$$So the exposed area $A$ cancels out and does not affect the loss per unit area.The heat energy lost per unit area depends on the temperature of the body, the temperature of the enclosure, and the nature and extent of the surface.The area of the exposed surface is not a factor.Answer:D. I, II and IV