- #1

babaliaris

- 112

- 15

Moved from technical forums, so no template

I'm new to thermodynamics and after some reading I tried to solve the problem below but I have stuck (I think this problem assumes you know only the first law of thermodynamics)

You have a piston resting on some stops inside a container filled with water and you want to find out after heating the container the final Temperature(T), the Work(w) that has been done and the Heat(q) that was transferred. The final state has 4 times more volume than the initial state.

I found the work with pressure constant by using the formula

w = -P ⋅ ΔV

but I don't know how to find the heat. I wrote down the first law

Δu = q+w

Also notice that in the above formula all quantities are per mass for some reason so the work which I calculated before probably needs to be divided by the pistons mass or something before I use it in this formula???

but I only know the work and the initial internal energy, I don't know the final internal energy so I can't find Δu => I can't find q.

Is there something that I'm missing? I used tables to find the internal energy (u) in the initial state (Notice in the picture that u (in red) is

You have a piston resting on some stops inside a container filled with water and you want to find out after heating the container the final Temperature(T), the Work(w) that has been done and the Heat(q) that was transferred. The final state has 4 times more volume than the initial state.

I found the work with pressure constant by using the formula

w = -P ⋅ ΔV

but I don't know how to find the heat. I wrote down the first law

Δu = q+w

Also notice that in the above formula all quantities are per mass for some reason so the work which I calculated before probably needs to be divided by the pistons mass or something before I use it in this formula???

but I only know the work and the initial internal energy, I don't know the final internal energy so I can't find Δu => I can't find q.

Is there something that I'm missing? I used tables to find the internal energy (u) in the initial state (Notice in the picture that u (in red) is

**kj/kg**).