Thermodynamics- energy, pressure, volume

In summary, the internal energy of a system increased by 1350J when it absorbed 1150J of heat energy at a constant pressure of 1.01E5 Pa. Using the first law of thermodynamics, we can find the work done on the system by subtracting the change in internal energy from the heat energy absorbed. This gives us a work value of 200J, which can then be used to find the change in volume of the system using the isobaric equation w=-P(change in V). The final answer is 2E-3m^3, which is the change in volume of the system.
  • #1
name_ask17
146
0

Homework Statement


The internal energy of a system increases by 1350J when the system absorbs 1150J of heat energy at a constant pressure of 1.01E5 Pa. By how much does the volume of the system change?


Homework Equations


Im not sure how to approach this but would i use the isobaric equation since the pressure is constant?
w=-P(change in V)


The Attempt at a Solution


I attempted to take the change in the work (1350) and divide out pressure, but that did not give me the correct answer.
(The answer should be 2E-3m^3, but i just don't know how to get there)
 
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  • #2
name_ask17 said:
I attempted to take the change in the work (1350)
That's not the work done on the system. (That's the total change in internal energy.)

(But your method is exactly right. Just find the correct value for the work and you'll be fine.)
 
Last edited:
  • #3
Doc Al said:
That's not the work done on the system. (That's the total change in internal energy.)

(But your method is exactly right. Just find the correct value for the work and you'll be fine.)

But I am still confused on what i am supposed to use for work
 
  • #4
name_ask17 said:
But I am still confused on what i am supposed to use for work
What does the 1st law of thermo tell you?
 
  • #5
U=q+w
 
  • #6
is that correct? and is so, how do i use that in this problem? i am confused.
 
  • #7
name_ask17 said:
U=q+w
Exactly. You're given U and q, so what's w?
 
  • #8
the answer to this problem should be 2E-3 but i can't seem to get that
 
  • #9
i just add them? but then i get the answr of .023. and that's not right
 
  • #10
name_ask17 said:
i just add them?
Add what?

U = ?
Q = ?

Solve for W.
 
  • #11
can you explain to me what i am doing wrong?
 
  • #12
which one is U? would it be the 1350?
 
  • #13
or would that be the q?
 
  • #14
name_ask17 said:
which one is U? would it be the 1350?
Yes, U = change in internal energy.
 
  • #15
so does that make the w 200?
 
  • #16
name_ask17 said:
so does that make the w 200?
Yes.
 
  • #17
thank you!
 

What is thermodynamics?

Thermodynamics is the branch of science that deals with the relationship between heat, energy, and work. It studies the behavior of systems that involve the transfer of energy as heat.

What is the first law of thermodynamics?

The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed, but can only be transferred or converted from one form to another.

How does pressure affect thermodynamics?

Pressure is a key factor in thermodynamics as it affects the volume and temperature of a system. An increase in pressure typically results in a decrease in volume and an increase in temperature, while a decrease in pressure leads to an increase in volume and a decrease in temperature.

What is the difference between internal and external energy in thermodynamics?

Internal energy refers to the total energy contained within a system, including both kinetic and potential energy of its particles. External energy, on the other hand, refers to the energy that is transferred in or out of the system as work or heat.

What is entropy in thermodynamics?

Entropy is a measure of the disorder or randomness of a system. It is a fundamental concept in thermodynamics and is closely related to the second law of thermodynamics, which states that the total entropy of a closed system will always increase over time.

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