Heat and the First Law of Thermodynamics

  • Thread starter cmilho10
  • Start date
  • #1
cmilho10
20
0
Consider Joule's apparatus described in Figure 20.1. Each of the two masses is 1.50 kg, and the tank is filled with 190 g of water. What is the increase in the temperature of the water after the masses fall through a distance of 3.50 m?

For this I know that PE=W, and that 2mgh is proportional to the change in temperature, but for some reason I can't get the correct answer

2(1.5 g)(9.8 m/s2)(3.5m)=103 C, but this is not correct
 

Answers and Replies

  • #2
Doc Al
Mentor
45,424
1,871
What you calculated is the work done in Joules, not the change in temperature. But the temperature change is proportional to the work done, but proportional does not mean equal. The relationship is as follows:
[tex]W = c m \Delta T[/tex]

Where c is the specific heat of water (look it up) and m is the mass of the water.
 
Last edited:

Suggested for: Heat and the First Law of Thermodynamics

  • Last Post
Replies
9
Views
4K
  • Last Post
Replies
2
Views
1K
Replies
1
Views
3K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
4
Views
2K
Replies
6
Views
4K
Replies
0
Views
3K
Replies
4
Views
3K
Replies
1
Views
1K
Replies
2
Views
14K
Top