500 J of work are done on a system in a process that decreases the system's thermal energy by 200 J. How much energy is transferred to or from the system as heat?

A 10% efficient engine accelerates a 1500 kg car from rest to 15 m/s. How much energy is transferred to the engine by burning gasoline?

600 J of heat energy are transferred to a system that does 400 J of work. By how much does the system's thermal energy change?

The planet Mercury's surface temperature varies from 700 K during the day to 90 K at night. What are these values in $^{\circ} \mathrm{C}$ and $^{\circ} \mathrm{F}$?

10 J of heat are removed from a gas sample while it is being compressed by a piston that does 20 J of work. What is the change in the thermal energy of the gas? Does the temperature of the gas increase or decrease?

A normal human body temperature can range from $33.2^{\circ} \mathrm{C}$ Blu to $38.2^{\circ} \mathrm{C}$. This range includes variations with gender, time of day, and where the measurement is taken. What is this range in ${ }^{\circ} \mathrm{F}$ ?

A piece of metal at $100 ^ { \circ } \mathrm { C }$ has its Celsius temperature doubled. By what factor does its kelvin temperature increase?

A heat engine does $20 \mathrm{~J}$ of work per cycle while exhausting $30 \mathrm{~J}$ of waste heat. What is the engine's thermal efficiency?

For locations that have no electric service, companies are designing bicycle-powered generators that are nearly 100% efficient that can be used to charge cell phones or power lights. If you are the person chosen to pedal and your friends need a total of $150 \mathrm{~W}$ of electric power, how much metabolic power will you use as you pedal?
A. $150 \mathrm{~W}$
B. $300 \mathrm{~W}$
C. $450 \mathrm{~W}$
D. $600 \mathrm{~W}$

A 1000 kg sports car accelerates from 0 to 30 m/s in 10 s. What is the average power of the engine?

A weightlifter curls a 30 kg bar, raising it each time a distance of 0.60 m. How many time must he repeat this exercise to burn off the energy in one slice of pizza?

300 J of energy are transferred to a system in the form of heat while the thermal energy increases by 150 J. How much work is done on or by the system?

When the sun's light hits the earth, the temperature rises. Is there an entropy change to accompany this transformation? Explain.

A newly proposed device for generating electricity from the sun is a heat engine in which the hot reservoir is created by focusing sunlight on a small spot on one side of the engine. The cold reservoir is ambient air at $20 ^ { \circ } \mathrm { C }$. The designer claims that the efficiency will be 60%. What minimum hot-reservoir temperature, in $^ { \circ } \mathrm { C }$, would be required to produce this efficiency?