Work and Energy of snow

In summary, a sled being pulled across a horizontal patch of snow with negligible friction experiences a 38% increase in kinetic energy when the pulling force is directed along the +x axis. If the force had been directed 62 degrees above the +x axis, the kinetic energy would have increased by 18%.
  • #1
kaspis245
189
1

Homework Statement


A sled is being pulled across a horizontal patch of snow. Friction is negligible. The pulling force points in the same direction as the sled's displacement, which is along the +x axis. As a result, the kinetic energy of the sled increases by 38% . By what percentage would the sled's kinetic energy have increased if this force had pointed 62o above the +x axis?

Homework Equations


The Work-Energy Theorem

The Attempt at a Solution


image.jpg


So I get, that the kinetic energy is reduced by 35% .

Correct answer: the kinetic energy increases by 18% .[/B]
 
Physics news on Phys.org
  • #2
kaspis245 said:
reduced
kaspis245 said:
Correct answer: the kinetic energy increases
If the problem statement is complete and correctly transcribed in your original post, without checking your math, you are correct. It would be best that you double-check the problem statement.
 
  • #3
The problem statement is correct 100%. Maybe I understood the problem incorrectly?
 
  • #4
As written, what you've done looks correct --- the x-component of the force is 100 % for the first case, and is reduced for the second. Looks like a really lousy problem statement, and an even worse job of proof-reading/checking matches of answers with problems. Let us know whether anyone fesses up, or how they rationalize the answer that's claimed.
 
  • #5
I think it is understanding indeed. I fail to understand what W0 represents, for example.
You are given that Ekin + F ##\cdot## s = 1.38 Ekin

Now try to grasp what you are being asked. The 17.8% book answer is correct.
 
  • #6
Wo represents work with which other works (W1 and W2) are compared.

I understand your method, but I don't understand why my method didn't work.
 
  • #7
Still don't understand. If you write W1 = F ##\cdot## s , then I don't understand why you consider that to be 138 % of W0 instead of 38%
 
  • #8
As the problem says, the kinetic energy of Wo increases by 38% .

If I say, that the very first energy, with which we will compare other energies, is equal to 100% , then the second energy W1, which is along +x axis, must be equal to 138% (increases by 38%) .
 
  • #9
Fine with me. But then you must write W1 = W0 + F ##\cdot## s.
There is no friction, the original kinetic energy doesn't go away.

And energies are not along any axis. Energies are numbers. But I understand what you mean.
 
  • Like
Likes skrat, kaspis245 and Bystander
  • #10
BvU has you pointed in the right direction --- stay with him, and forget everything I said --- I misread the problem horribly.
 

1. What is the relationship between work and energy of snow?

The work done on snow is directly related to the energy it possesses. When work is done on snow, such as when it is compacted or moved, it gains potential energy. This potential energy can later be converted into kinetic energy when the snow is released or slides down a slope.

2. How does temperature affect the work and energy of snow?

Temperature plays a significant role in the work and energy of snow. Cold temperatures can increase the potential energy of snow, making it more likely to collapse or slide. On the other hand, warm temperatures can decrease the potential energy of snow, making it easier to compact and manipulate.

3. Can the work and energy of snow be harnessed for human use?

Yes, the work and energy of snow can be harnessed for human use. For example, ski resorts use snowmaking machines to create artificial snow by compressing and spraying water into cold temperatures, increasing the potential energy of the snow. Snow can also be used for hydroelectric power when melted and channeled into turbines.

4. How does the shape and form of snow affect its work and energy?

The shape and form of snow can greatly impact its work and energy. For example, fluffy, powdery snow has a higher potential energy than dense, compacted snow due to the air pockets within it. Different shapes, such as snowflakes or snowballs, also have varying potential and kinetic energies.

5. What is the role of friction in the work and energy of snow?

Friction can both increase and decrease the work and energy of snow. For instance, friction between snow particles can cause compaction, reducing the potential energy of the snow. However, friction between snow and a surface, such as a ski slope, can create kinetic energy and allow for movement and sliding.

Similar threads

  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
972
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
1K
Replies
1
Views
461
  • Introductory Physics Homework Help
Replies
6
Views
8K
  • Introductory Physics Homework Help
Replies
4
Views
4K
  • Introductory Physics Homework Help
Replies
6
Views
3K
Back
Top