First law of Thermodynamics: Easy Solutions with Examples

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Thermal Physics
First law of Thermodynamics

Recent questions in First law of Thermodynamics

Moselq8 2022-08-15

Show that the work performed by an engine during an irreversible cycle operating between two thermal reservoirs at temperatures $T_{1}$ and $T_{2} < T_{1}$ is given by $W = W_{m a x} - T_{2} Δ S$ , where $Δ S$ is the increase of entropy of the Universe, and $W_{m a x}$ is the corresponding work performed in a reversible Carnot cycle.

Jaxson Mack 2022-08-14

After you drive for a while your tires will gain some energy via friction and heat up. If the air inside the tires absorbs 150 Joules of energy by heat, and does 100 Joules of work by expanding and lifting your car a fraction of a millimeter, what is the net change in the internal energy of the air inside the tires? (Hint: Use the first law of thermodynamics) 100 Joules 50 Joules 250 Joules 150 Joules

trokusr 2022-08-14

Consider the following processes: The temperature of two identical gases is increased from the same initial temperature to the same final temperature. Reversible processes are used. For gas A the process is carried out at constant volume while for gas B it is carried out at constant pressure. The change in entropy:
a. Is the same for A and B
b. Is greater for A
c. Is greater for B
d. Is greater for A only if the initial temperature is low

patylomy7 2022-08-13

A work done on the steady flow system is 30 kJ/kgm. Calculate the heat in HP if the mass flow rate of fluid is 10 kg per minute given that the internal energy is decreased by 10 kJ/kgm and the fluid flow is increased by 20 kJ/kgm. Also, identify if the heat is added to the system or rejected by the system.

orkesruim40 2022-08-13

For each of the cases below, determine if the heat engine satisfies the first law and if it violates the second law of thermodynamics in
$Q_{H} = 6 kW Q_{L} = 4 kW W = 2 kW Q_{H} = 6 kW Q_{L} = 0 kW W = 6 kW$

Brylee Shepard 2022-08-11

Is heat $δ Q$ an exact differential for an isochoric process (ideal gases)?

Garrett Sheppard 2022-08-11

In the first law of thermodynamics, we learned that W and Q are path-dependent quantities, but how are Q and W defined?

Makayla Eaton 2022-08-10

My question is, why do bodies tend to attain thermal equilibrium in the first place? Is it a consequence of the 2nd Law of Thermodynamics? (Regarding the entropy of the universe?)

Dorsheele0p 2022-08-10

a) According to the First Law of Thermodynamics, how much did the thermal energy of a system change if we did 1500 J of work on the system, while the system lost 750 J of heat to the environment? b) A heat engine extracts 55 kJ from the hot reservoir and exhausts 40 kJ into the cold reservoir. How much work was done and what is the efficiency, e?

Holzkeulecz 2022-08-10

A closed system which creates work done by expansion is 50 km and decrease internal energy is 30kj then what is heat transfer during process.
A. -20kj
B. + 20 kj
C. - 80 kj
D. + 80 kj

essam mohamed2022-08-06

A person weighs a fish of mass m = 40.0 N on a spring scale attached to the ceiling of an elevator. Show that if the elevator accelerates either upward or downward,
with a = 2.00 m/s2, the spring scale gives a reading that is different from the weight of the fish.

Mariah Sparks 2022-07-23

Why is small work done always taken as $d W = F \cdot d x$ and not $d W = x \cdot d F$ ?

Aphroditeoq 2022-07-22

When an isolated ideal gas gets (adiabatically) compressed due to its own gravity, its gravitational potential energy increases. Does this mean its kinetic energy will reduce (due to conservation of total energy) and the gas will cool down? Does it not violate first law of thermodynamics which says an ideal gas should heat up on compression?

Emmanuel Pace 2022-07-22

So I was doing problem and used formula Eq.1 to find Energy in isochoric process.
$Δ E = \frac{3}{2} p V$
and get a bad result so now i saw the correct formula:
$Δ E = n c_{v} Δ T$
What is doing on? can somebody link consistent source of that formulas etc.?

agantisbz 2022-07-22

Consider the following reaction in the vessel with a movable piston. $X (g) + Y (g) \to Z (s)$ For this reaction, $△ u = 286 J$ , the piston moves up, and the system absorbs 388 J of heat from its surroundings.(a) Does the system do work? (b) How much work?

Nash Frank 2022-07-22

Change in state {for example from liquid to gas} is an isothermal process but the change in internal energy is not zero in this process isn't this contradictory?

Taniya Burns 2022-07-22

Deriving $P V^{n} = constant$ for polytropic processes?

Almintas2l 2022-07-20

Why can $β$ not be linearly proportional to T, that is $β = c o n s t a n t \times T$

ingwadlatp 2022-07-20

Is enthalpy also valid for liquids and solids?

Luciano Webster 2022-07-19

What is the First Law of Thermodynamics? Give 1 situation wherein the first law can be applied and explain how it is applied.

Are you looking for help understanding the first law of thermodynamics? This fundamental law of physics is essential to understand the transfer of energy and heat. You can find answers to your questions here, as well as some equations to help you understand it better. The first law of thermodynamics is a statement of the conservation of energy. It states that energy can neither be created nor destroyed. This means that the total amount of energy in an isolated system remains constant. You can use this law to calculate the amount of energy transferred or converted in a given process. Whether you are a student or a professional, understanding the first law of thermodynamics is essential. Get help with questions, equations and answers in our math site.

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