(a) Calculate the rate of heat conduction through house walls that are 13.0 cm thick and have an average thermal conductivity twice that of glass wool. Assume there are no windows or doors. The walls’ surface area is $120 \mathrm { m } ^ { 2 }$ and their inside surface is at $18.0 ^ { \circ } \mathrm { C }$, while their outside surface is at $5.00 ^ { \circ } \mathrm { C }$. (b) How many 1-kW room heaters would be needed to balance the heat transfer due to conduction?

The rate of heat conduction out of a window on a winter day is rapid enough to chill the air next to it. To see just how rapidly the windows transfer heat by conduction, calculate the rate of conduction in watts through a $3.00 - m ^ { 2 }$ window that is 0.634 cm thick (1/4 in.) if the temperatures of the inner and outer surfaces are $5.00 ^ { \circ } \mathrm { C }$ and $- 10.0 ^ { \circ } \mathrm { C }$, respectively. (This rapid rate will not be maintained—the inner surface will cool, even to the point of frost formation.)

Give three example solutions that fit each of the following descriptions. a strong electrolyte solution that is slightly acidic

A firewalker runs across a bed of hot coals without sustaining burns. Calculate the heat transferred by conduction into the sole of one foot of a firewalker given that the bottom of the foot is a $3.00 \mathrm{~mm}$ thick callus with a conductivity at the low end of the range for wood and its density is $300 \mathrm{~kg} / \mathrm{m}^3$. The area of contact is $25.0 \mathrm{~cm}^2$, the temperature of the coals is $700^{\circ} \mathrm{C}$, and the time in contact is $1.00 \mathrm{~s}$. Ignore the evaporative cooling of sweat.

Determine which sets are the empty set. $\{x | x \in \mathbf{N}$ and 2<x<5}

A bag containing $0 ^ { \circ } \mathrm { C }$ ice is much more effective in absorbing energy than one containing the same amount of $0 ^ { \circ } \mathrm { C }$ water. (a) How much heat transfer is necessary to raise the temperature of 0.800 kg of water from $0 ^ { \circ } \mathrm { C }$ to $30.0 ^ { \circ } \mathrm { C }$? (b) How much heat transfer is required to first melt 0.800 kg of $0 ^ { \circ } \mathrm { C }$ ice and then raise its temperature? (c) Explain how your answer supports the contention that the ice is more effective.

Before going in for his annual physical, a 70.0-kg man whose body temperature is $37.0^{\circ} \mathrm{C}$ consumes an entire 0.355-L can of a soft drink (mostly water) at $12.0^{\circ} \mathrm{C}$.

What will his body temperature be after equilibrium is attained? Ignore any heating by the man’s metabolism. The specific heat of the man’s body is $3480 \mathrm{J} / \mathrm{kg} \cdot \mathrm{K}$.

A bag containing $0^{\circ} \mathrm{C}$ ice is much more effective in absorbing energy than one containing the same amount of $0^{\circ} \mathrm{C}$ water.

How much heat transfer is required to first melt 0.800 kg of $0^{\circ} \mathrm{C}$ ice and then raise its temperature?

How much heat transfer (in kilocalories) is required to thaw a 0.450-kg package of frozen vegetables originally at $0 ^ { \circ } \mathrm { C }$ if their heat of fusion is the same as that of water?

A logo in an advertisement is an equilateral triangle with a side length of 7 cm. Sketch the logo and give measure of each side.

The same heat transfer into identical masses of different substances produces different temperature changes. Calculate the final temperature when 1.00 kcal of heat transfers into 1.00 kg of the following, originally at $20.0 ^ { \circ } \mathrm { C }$: (a) water; (b) concrete; (c) steel; and (d) mercury.

A bag containing $0^{\circ} \mathrm{C}$ ice is much more effective in absorbing energy than one containing the same amount of $0^{\circ} \mathrm{C}$ water.

Explain how your answer supports the contention that the ice is more effective.

A 4-m $\times 5-m \times 6-m$ room is to be heated by a baseboard resistance heater. It is desired that the resistance heater be able to raise the air temperature in the room from 5 to $25^{\circ} \mathrm{C}$within 11 min. Assuming no heat losses from the room and an atmospheric pressure of 100 kPa, determine the required power of the resistance heater. Assume constant specific heats at room temperature.

Consider a similar plot for rocks ejected from Mars. Where would this plot intercept the $x$ axis? A. The plot for Mars would intercept the $x$ axis at $5.0 \mathrm{~km} / \mathrm{s}$. B. The plot for Mars would intercept the $x$ axis at $16.2 \mathrm{~km} / \mathrm{s}$. C. The plot for Mars would intercept the $x$ axis at $11.2 \mathrm{~km} / \mathrm{s}$. D. The plot for Mars would not intercept the $x$ axis.