Thermodynamics- energy, pressure, volume

[name_ask17]

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)

 

[Doc Al]

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.)

 

[name_ask17]

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

 

[Doc Al]

But I am still confused on what i am supposed to use for work

What does the 1st law of thermo tell you?

 

[name_ask17]

U=q+w

 

[name_ask17]

is that correct? and is so, how do i use that in this problem? i am confused.

 

[Doc Al]

U=q+w

Exactly. You're given U and q, so what's w?

 

[name_ask17]

the answer to this problem should be 2E-3 but i can't seem to get that

 

[name_ask17]

i just add them? but then i get the answr of .023. and that's not right

 

[Doc Al]

i just add them?

Add what?

U = ?
Q = ?

Solve for W.

 

[name_ask17]

can you explain to me what i am doing wrong?

 

[name_ask17]

which one is U? would it be the 1350?

 

[name_ask17]

or would that be the q?

 

[Doc Al]

which one is U? would it be the 1350?

Yes, U = change in internal energy.

 

[name_ask17]

so does that make the w 200?

 

[Doc Al]

so does that make the w 200?

Yes.

 

[name_ask17]

thank you!