Will All the Ice Melt in a Box with a Heat Capacity of 80J/K?

  • Thread starter Thread starter Izekid
  • Start date Start date
Click For Summary
The discussion revolves around calculating whether 0.050 kg of ice at -15°C will completely melt when placed in a box containing 0.2 kg of water at 18°C, with the box having a heat capacity of 80 J/K. The initial calculations involve determining the heat energy available from the water and the box, which totals approximately 838 J, and comparing it to the energy needed to raise the ice's temperature to 0°C and then melt it. The required energy to raise the ice to 0°C is calculated as 209.5 J, but further analysis is needed to determine if the remaining energy after cooling the water to 0°C is sufficient to melt the ice. The key question remains whether the total energy released by the water and box when cooling from 18°C to 0°C exceeds the energy required to melt the ice. Ultimately, the conclusion hinges on comparing these energy values to ascertain if all the ice will melt.
Izekid
Messages
40
Reaction score
0
Here's my problem

A box with the heathcapacity 80J/K contains 0,2kg water. The box and the water has together the temperatur 18*C. We put 0,050kg ice with the temperature -15*C in the box of water. Investigate if all ice melts. Don't take with heath from the surrondings.

Well for this problem I though like this

0,2Kg Water * 4,19(water's heath capacity) = 0,838 + 80J/K =0,8380008

Then I took the Ice capacity = 0,050kg * 4,19 = 0,2095

0,8380008-0,2095 =0,62858

Then let's do it to Kelvin 273+18=291K
273-15=258K

0,62858 * -33 K = -20,7314

But that doesn't say me nothing if the Ice has melted?

How do I know that?
 
Physics news on Phys.org
Think this way: How much energy is required to melt the ice? You must first raise the temperature from -15 to 0, then melt it.

Now ask: Does the box + water have enough energy to melt that ice? How much energy will the box + water release if it cooled from 18 degrees to 0?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

Similar threads

  • · Replies 6 ·
Replies
6
Views
526
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 17 ·
Replies
17
Views
5K
Replies
11
Views
2K
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
12
Views
2K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 4 ·
Replies
4
Views
4K