# Energy conservation (potential, kinetic, spring)

• jegues
In summary: From there, you will be able to find a link to the homework forum. You will be able to find the free body diagram and the question I'm asking there.
jegues
Hello again,

The question and free body diagram as well as my attempt at the solution are all in the attached photo.

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• springquestion.JPG
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My last thread was moved, I'm assuming I posted this one in the wrong place as well, sorry!

jegues said:
Hello again,

The question and free body diagram as well as my attempt at the solution are all in the attached photo.

Watch out. If you use x for the vertical distance shown in your figure, the spring is not compressed a distance x! Do you see why?

The variable I should be using in the calculation for the Usf (final spring energy) should be r, where r is defined as follows, r = x/sin(theta) correct?

jegues said:
The variable I should be using in the calculation for the Usf (final spring energy) should be r, where r is defined as follows, r = x/sin(theta) correct?

That's it!

Thanks again friend, I seem to only need the slightest push in order to figure out where I went wrong.

jegues said:
Thanks again friend, I seem to only need the slightest push in order to figure out where I went wrong.

You're welcome. That's a good sign, you know? Because it means that you just need to see the little tricks to complete the problem and once you know the trick, you are all set for other problems. Some people need help with all the steps, from the very beginning. So I would say that you are doing very well!

Hmmm... Apparently I still can't get to the correct answer.

I'm using the equation:

mgh + mgx - 1/2k(r)^2 = 0; Giving me,

-16(x^2) + 0.784x + 0.4704 = 0; This doesn't seem to give me the correct zeros?

The answer that equation gives you is the vertical compression of the spring. You need to find the compression along the slope of the incline.

jegues said:
My last thread was moved, I'm assuming I posted this one in the wrong place as well, sorry!
FYI for in future: from the Physics Forums main page, look for "Homework and Coursework Questions" and click there.

## 1. What is energy conservation?

Energy conservation is the principle that energy cannot be created or destroyed, but can only be transferred or converted from one form to another. This means that the total amount of energy in a closed system remains constant over time.

## 2. What are potential and kinetic energy?

Potential energy is the energy stored in an object due to its position or state. It can be gravitational, elastic, or chemical potential energy. Kinetic energy, on the other hand, is the energy an object possesses due to its motion. It is directly proportional to the mass and square of velocity of the object.

## 3. How is energy conserved in a spring?

When a spring is compressed or stretched, it stores potential energy. This energy is then converted into kinetic energy as the spring returns to its original length. Due to the law of conservation of energy, the total energy in the spring remains the same throughout this process.

## 4. How can we conserve energy in our daily lives?

There are many ways to conserve energy in our daily lives, such as turning off lights and appliances when not in use, using energy-efficient light bulbs and appliances, carpooling or using public transportation, and reducing the use of heating and cooling systems.

## 5. Why is energy conservation important?

Energy conservation is important because it helps reduce our carbon footprint and preserve natural resources. It also helps save money on energy bills and promotes sustainability for future generations. Moreover, by conserving energy, we can reduce our dependence on non-renewable sources of energy and mitigate the negative impacts of climate change.

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