# Cons. of Energy, momentum ,and impact.

• pyroknife
In summary, the problem involves finding the velocity of an anvil using the conservation of energy and the formula T=KE. The question arises why the term 29.4(10^3)(0.024) is included in the equation, as it represents the potential energy of gravity. The answer is that the anvil has a mass of 3000kg, so its force and distance must be accounted for in the calculation. However, the given solution includes both the gravitational potential energy and subtracts it, making it a questionable method. This could be an attempt to match the given answer or a mistake in the original solution.
pyroknife
I attached the problem statement only with PART of the solutions.
He is using the conservation of energy to find the velocity of the anvil.
T=Kinetic energy
V sub e=potential energy of the spring
V sub g=potential energy of gravity

The part I am not understand is how ΔV sub e = 1/2(2.8*10^6)(0.024)^2+29.4(10^3)(0.024) J

Why do they have the 29.4(10^3)(0.024) there?? That's potential energy of gravity. My professor said the answer was right and that he has checked over it, but he takes a long time to respond so I'm asking it on here.

#### Attachments

• Untitled.jpg
28.9 KB · Views: 487
That's because the springs have a massive 3000kg anvil on it. So you have to account for the force of that on it and the distance it has moved as well.

So when that spring is released, it's moving itself as well as the anvil, to account for that extra energy you have to include the anvil.

NewtonianAlch said:
That's because the springs have a massive 3000kg anvil on it. So you have to account for the force of that on it and the distance it has moved as well.

So when that spring is released, it's moving itself as well as the anvil, to account for that extra energy you have to include the anvil.

The problem is, the given solution first includes the gravitational PE with the spring PE, then subtracts it again under the separate guise of gravitational PE. Thus the gravitational PE is essentially being ignored entirely for the anvil/spring compression.

I'd call this highly suspicious behavior! It looks like a fudge to make the solution match the given answer. Perhaps whoever provided the book answer simply forgot to include gravitational PE when they solved it, and now the only way to match the "correct" answer is to recreate their error.

## 1. What is the law of conservation of energy?

The law of conservation of energy states 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.

## 2. How does the conservation of energy apply to everyday life?

The conservation of energy applies to everyday life in various ways. For example, when we turn on a light switch, electrical energy is converted into light and heat energy. When we ride a bike, our body's chemical energy is converted into kinetic energy. This law also explains why we must conserve resources, as they are forms of energy that can be converted and used in different ways.

## 3. What is the law of conservation of momentum?

The law of conservation of momentum states that the total momentum of a closed system remains constant, as long as there are no external forces acting on the system. This means that in a collision or explosion, the total momentum before and after the event remains the same.

## 4. How does the conservation of momentum apply to collisions and impacts?

In collisions and impacts, the law of conservation of momentum can be used to calculate the velocities of the objects involved. The total momentum before the collision is equal to the total momentum after the collision. This law helps us understand and predict the outcomes of collisions between objects.

## 5. What are some real-life examples of the conservation of energy, momentum, and impact?

Some examples of the conservation of energy include a pendulum swinging back and forth, a rollercoaster ride, and a chemical reaction. For momentum, a game of billiards, a car crash, and a rocket launch are all examples of the conservation of momentum. For impact, a basketball bouncing off the ground, a hammer hitting a nail, and a tennis ball hitting a racket all demonstrate the principles of conservation of energy, momentum, and impact.

• Introductory Physics Homework Help
Replies
55
Views
3K
• Introductory Physics Homework Help
Replies
7
Views
211
• Introductory Physics Homework Help
Replies
15
Views
462
• Introductory Physics Homework Help
Replies
3
Views
601
• Introductory Physics Homework Help
Replies
10
Views
1K
• Introductory Physics Homework Help
Replies
7
Views
1K
• Introductory Physics Homework Help
Replies
1
Views
854
• Introductory Physics Homework Help
Replies
20
Views
2K
• Introductory Physics Homework Help
Replies
5
Views
1K
• Introductory Physics Homework Help
Replies
3
Views
1K