Based on the mechanisms of heat transfer, list three reasons why energy transfer by heat may be negligible.

The heat capacity, $C$, of an object is defined as the amount of heat needed to raise its temperature by $1 \mathrm{C}^{\circ}$. Thus, to raise the temperature by $\Delta T$ requires heat $Q$ given by

$$Q=C \Delta T \text {. }$$

$(c)$ What is the heat capacity of $38 \mathrm{~kg}$ of water?

The performance of a heat pump degrades (i.e., its COP decreases) as the temperature of the heat source decreases. This makes using heat pumps at locations with severe weather conditions unattractive. Consider a house that is heated and maintained at $20^{\circ} \mathrm{C}$ by a heat pump during the winter. What is the maximum COP for this heat pump if heat is extracted from the outdoor air at (a) $10^{\circ} \mathrm{C},$ (b) $-5^{\circ} \mathrm{C},$ and (c) $-30^{\circ} \mathrm{C} ?$

Although both ends of a microtubule can gain or lose subunits, one end ( called the plus end) polymerizes and depolymerizes at a higher rate than the other end (the minus end). For spindle microtubules, the plus ends are in the center of the spindle, and the minus ends are at the poles. Motor proteins that move along microtubules specialize in walking either toward the plus end or toward the minus end; the two types are called plus nd-directed and minus end-directed motor proteins, respectively. Given what you know about chromosome movement and spindle changes during anaphase, predict which type of motor proteins would be present on kinetochore microtubules.

A double-pipe parallel-flow heat exchanger is used to heat cold tap water with hot water. Hot water $\left(c_{p}=4.25 \mathrm{kJ} / \mathrm{kg} \cdot \mathrm{K}\right)$ enters the tube at $85^{\circ} \mathrm{C}$ at a rate of 1.4 kg/s and leaves at $50^{\circ} \mathrm{C}.$ The heat exchanger is not well insulated, and it is estimated that 3 percent of the heat given up by the hot fluid is lost from the heat exchanger. If the overall heat transfer coefficient and the surface area of the heat exchanger are $1150 \mathrm{W} / \mathrm{m}^{2} \cdot \mathrm{K}$ and $4 \mathrm{m}^{2},$ respectively, determine the rate of heat transfer to the cold water and the log mean temperature difference for this heat exchanger.

What is heat?

The heat capacity, $C$, of an object is defined as the amount of heat needed to raise its temperature by $1 \mathrm{C}^{\circ}$. Thus, to raise the temperature by $\Delta T$ requires heat $Q$ given by

$$Q=C \Delta T \text {. }$$

What is the heat capacity of $1.0 \mathrm{~kg}$ of water?

Which of the following statements about the small intestine is false? a. Absorptive cells that line the small intestine have microvilli, small projections that increase surface area and aid in the absorption of food. b. The inside of the small intestine has many folds, called villi. c. Microvilli are lined with blood vessels as well as lymphatic vessels. d. The inside of the small intestine is called the lumen.

After you eat a protein bar, which chemical reactions must occur for the amino acids in the protein bar to be converted into proteins in your body cells?

A heat engine receives $1 \mathrm{~kW}$ of heat transfer at $1000 \mathrm{~K}$ and gives out $600 \mathrm{~W}$ as work, with the rest as heat transfer to the ambient. What are the fluxes of exergy in and out?

How much energy must the shock absorbers of a 1200-kg car dissipate in order to damp a bounce that initially has a velocity of 0.800 m/s at the equilibrium position? Assume the car returns to its original vertical position.

Although both ends of a microtubule can gain or lose subunits, one end ( called the plus end) polymerizes and depolymerizes at a higher rate than the other end (the minus end). For spindle microtubules, the plus ends are in the center of the spindle, and the minus ends are at the poles. Motor proteins that move along microtubules specialize in walking either toward the plus end or toward the minus end; the two types are called plus nd-directed and minus end-directed motor proteins, respectively. Given what you know about chromosome movement and spindle changes during anaphase, predict which type of motor proteins would be present on nonkinetochore microtubules.

Concern these notions of temperature, heat, and heat flux density. Use Gauss’s theorem to derive the heat equation, $\sigma \rho \frac{\partial T}{\partial t}=k \nabla^{2} T$.

Is the total amount of heat released by a heat engine to the low-temperature reservoir in one cycle ever greater than the amount of heat taken in from the high-temperature reservoir in one cycle? Explain.