In a flask, 114.0 g of water is heated using $67.0 \mathrm {~W}$ of power, with perfect efficiency. How long will it take to raise the temperature of the water from $15 ^ { \circ } \mathrm { C }$ to $25 ^ { \circ } \mathrm { C } \text { ? }$ The specific heat of water is 4186 J/kg ∙ K.
A) 71 s
B) 4.1 s
C) 17 s
D) 320,000 s

Question

Quizplus · Accepted Answer

The energy required to raise the temperature is calculated using $Q = mc\Delta T$. For 114 g of water, $m = 0.114 \, \text{kg}$, $c = 4186 \, \text{J/kg} \cdot \text{K}$, and $\Delta T = 10 \, \text{K}$. Thus, $Q = 0.114 \times 4186 \times 10 = 4772.4 \, \text{J}$. With a power of 67 W, time $t = \frac{Q}{P} = \frac{4772.4}{67} \approx 71 \, \text{s}$.

In a Flask, 114 67.0 W67.0 \mathrm {~W}67.0 W Of Power, with Perfect Efficiency

In a Flask, 114 $67.0 \mathrm {~W}$ Of Power, with Perfect Efficiency