A model aircraft internal-combustion engine produces $10 \mathrm{~W}$ of power. How much power is this in $(a) \mathrm{lbf} \cdot \mathrm{ft} / \mathrm{s}$ and $(b) \mathrm{hp}$ ?

Consider a river flowing toward a lake at an aver- age velocity of 3 m/s at a rate of $500 m^3/s$ at a location 90 m above the lake surface. Determine the total mechanical energy of the river water per unit mass and the power generation potential of the entire river at that location.

A small electrical motor produces $10 \mathrm{~W}$ of mechanical power. What is this power in $(a) \mathrm{N}, \mathrm{m}$, and $\mathrm{s}$ units; and $(b) \mathrm{kg}$, $\mathrm{m}$, and $\mathrm{s}$ units? Answers: (a) $10 \mathrm{~N} \cdot \mathrm{m} / \mathrm{s}$, (b) $10 \mathrm{~kg} \cdot \mathrm{m}^{2} / \mathrm{s}^{3}$

A personal computer is to be examined from a thermodynamic perspective. Find the direction of the work and heat transfers (in or out) when the $(a)$ keyboard, $(b)$ monitor, $(c)$ processing unit, and $(d)$ all of these are taken as the system.

Determine the reactions at the beam supports for the given loading

Consider an electric refrigerator located in a room. Find the direction of the work and heat interactions (in or out) when the following are taken as the system: $(a)$ the contents of the refrigerator, $(b)$ all parts of the refrigerator including the contents, and $(c)$ everything contained within the room during a winter day.

The length of a spring can be changed by $(a)$ applying a force to it or $(b)$ changing its temperature (i.e., thermal expansion). What type of energy interaction between the system (spring) and surroundings is required to change the length of the spring in these two ways?

Consider an automobile traveling at a constant speed along a road. Find the direction of the heat and work interactions, taking the following as the system: $(a)$ the car radiator, $(b)$ the car engine, $(c)$ the car wheels, $(d)$ the road, and $(e)$ the air surrounding the car.

What is the caloric theory? When and why was it abandoned?

What are point and path functions? Give some examples.

What is an adiabatic process? What is an adiabatic system?

When is the energy crossing the boundaries of a closed system heat and when is it work?

Natural gas, which is mostly methane $\mathrm{CH}_{4}$, is a fuel and a major energy source. Can we say the same about hydrogen gas, $\mathrm{H}_{2}$ ?

Fencing a lot A farmer wants to fence the perimeter of a rectangular lot with an area of $1600$ square feet. If the lot is $x$ feet long, express the number of feet $L$ of fence needed as a function of $x$.