55 J of heat energy are transferred into an ideal gas and 40 J of work is done on the gas. What is the change in thermal energy, in Joules? Your answer needs to have 2 significant figures, including the negative sign in your answer if needed. Do not include the positive sign if the answer is positive. No unit is needed in your answer, it is already given in the question statement.

55 J of heat energy are transferred into an ideal gas and 40 J of work is done on the gas. What is the change in thermal energy, in Joules? Your answer needs to have 2 significant figures, including the negative sign in your answer if needed. Do not include the positive sign if the answer is positive. No unit is needed in your answer, it is already given in the question statement.

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter15: Thermodynamics

Section: Chapter Questions

Problem 42PE: (a) What is the best coefficient of performance for a refrigerator that cools an environment at...

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(a) What is the best coefficient of performance for a refrigerator that cools an environment at 30.0C and has heat transfer to another environment at 45.0C ? (b) How much work in joules must be done for a heat transfer of 4186 kJ from the cold environment? (c) What is the cost of doing this if the work costs 10.0 cents per 3.60106J (a kilowatthour)? (d) How many kJ of heat transfer occurs into the warm environment? (e) Discuss what type of refrigerator might operate between these temperatures.
(a) How much food energy will a man metabolize in the process of doing 35.0 kJ of work with an efficiency of 5.00%? (b) How much heal transfer occurs to the environment to keep his temperature constant? Explicitly show how you follow the steps in the Problem—Solving Strategy for thermodynamics found in Problem-Solving Strategies for Thermodynamics.
(a) How long will the energy in a 1470kJ (350kcal) cup of yogurt last in a woman doing work at the rate of 150 W with an efficiency of 20.0% (such as in leisurely climbing stairs)? (b) Does the time found in part (a) imply that it is easy to consume more food energy than you can reasonably expect to work off with exercise?
A power plant has been proposed that would make use of the temperature gradient in the ocean. The system is to operate between 20.0C (surface water temperature) and 5.00C (water temperature at a depth of about 1 km). (a) What is the maximum efficiency of such a system? (b) If the useful power output of the plant is 75.0 MW, how much energy is absorbed per hour? (c) In view of your answer to part (a), do you think such a system is worthwhile (considering that there is no charge for fuel)?
600 J of work is done on a system in a process that decreases the thermal energy of the system by 300 J . How much heat energy is transferred to or from the system as heat? Enter positive value if the energy is transferred to the system and negative if the energy is transferred from the system. Express your answer in joules.
The food calorie, equal to 4186 JJ, is a measure of how much energy is released when food is metabolized by the body. A certain brand of fruit-and-cereal bar contains 145 food calories per bar. A. If a 71.0 kgkg hiker eats one of these bars, how high a mountain must he climb to "work off" the calories, assuming that all the food energy goes only into increasing gravitational potential energy? Express your answer in meters. H=____________m B. If, as is typical, only 25.0 %% of the food calories go into mechanical energy, what would be the answer to part A? (Note: In this and all other problems, we are assuming that 100%% of the food calories that are eaten are absorbed and used by the body. This is actually not true. A person's "metabolic efficiency" is the percentage of calories eaten that are actually used; the rest are eliminated by the body. Metabolic efficiency varies considerably from person to person.) Express your answer in meters. H=______________m
In the pV diagram shown in the figure (Figure 1), 80.0 J of work was done by 0.0610 mole of ideal gas during an adiabatic process. a) How much heat entered or left this gas from a to b? Express your answer in joules. b) By how many joules did the internal energy of the gas change? Express your answer in joules. c) What is the temperature of the gas at b? Express your answer in kelvins.
give a specific example of a process that has the energy changes and transfers described. (For example, if the question states “ΔEth > 0, W = 0,” you are to describe a process that has an increase in thermal energy and no transfer of energy by work. You could write “Heating a pan of water on the stove.”) ΔEth = 0, W ≠ 0, Q ≠ 0
16 J of heat energy is transferred into an ideal gas and 59 J of work is done on the gas. What is the change in thermal energy, in Joules?
A food calorie is a unit of energy such that 1 food calorie = 4184 J. This means that a person that burns energy with a power of 4184 W would burn one food calorie every second. A more typical human power rate is 90 W (called the basal metabolic rate). At this rate, how many calories are burned per second (or alternatively, how many seconds does it take to burn 1 calorie)?
Why are energy equations important in Thermodynamics? Give 5 reasons.
1A) The amount of work that can be performed by a process under certain conditions is given by ∆G for that process. What are the conditions?1B) Likewise, the amount of work that can be done by a process ocurring undercertain (other) conditions equals ∆A, where A is the Helmholtz free energy.What are the conditions?