Conservation of energy question -

In summary: Or maybe the working is wrong? I can see that the E answer the image seems to be the same as the D working, but the working is not consistent with the D answer shown. It's not clear to me which is wrong.
  • #1
KieronB
1
0
A cylindrical container of water has a diameter of 7.98 m and a perpendicular height of 2 m. It is filled with water (1000 kg = 1000 l) and placed on top of a 4 m stand. Calculate the:
A) potential energy of the water
B) kinetic energy of 20 kg of water just before it reaches the ground, if the container over flows.
C) velocity when the 20kg reaches the ground.
D) potential energy of the top half of the water.
E) potential energy of the bottom half of the water.

Answers:
A) 4.901 MJ
B) 1176 J ------->I was able to solve this one
C) 10.844 m/s ---->I was able to solve this one aswell
D) 2.696 MJ
E) 2.696 MJ

Thank you :oldsmile:
15175833766741676587289.jpg


 

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  • #2
It is hard to read your work, can you type it out?

Your potential energy seems way off. It looks like you inserted a very large number in for the mass and I'm not sure where that came from. Also, you used 4m as the height of the water. The problem is that much of the water is higher than 4m above the ground. The correct distance will be the average high of the water.

I think part B is ok.

I don't see your work for the following parts.
 
  • #3
Hello Kieron, :welcome:

Please don't delete the template. See PF guidelines

Also: post your work in detail, not just the answers (or are these the book answers ?)

Then: what is your question ?

@NFuller claims PE 4.9 MJ is way off; I 'think' it's still low :smile: [edit] correct but with too many decimals.

[edit] from you r D and E I'd say they are at the same height. Strange :rolleyes:
 
  • #4
As others have remarked, the image is too faint, and it is unclear whether the answers listed are your own or from the book.
For A, I agree with the 4.9MJ answer posted, but in the image you seem to have a lower number as a result of using the wrong average height. The working seems to include a mass value something like 100028, but perhaps I am misreading it.
The D answer posted is consistent with the A answer, but E is not. Maybe you looked at the wrong number when typing the post?
 

Related to Conservation of energy question -

What is the conservation of energy?

The conservation of energy is a fundamental principle in physics that states that energy cannot be created or destroyed, but can only be converted from one form to another.

Why is the conservation of energy important?

The conservation of energy is important because it allows us to understand and predict the behavior of physical systems. It also plays a crucial role in many scientific and technological advancements.

What are some examples of the conservation of energy in everyday life?

Some examples of the conservation of energy in everyday life include turning on a light bulb, riding a bike, and using a battery-powered device. In all of these cases, energy is converted from one form to another, but the total amount of energy remains constant.

Is the conservation of energy a universal law?

Yes, the conservation of energy is considered a universal law in physics. It has been extensively tested and has been found to hold true in all physical systems and processes.

Can energy be lost or wasted?

No, according to the conservation of energy, energy cannot be lost or wasted. It can only be converted from one form to another, but the total amount of energy remains constant.

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